[v2,1/3] mmc: sdhci: add support for using external DMA devices

Message ID 1542007566-9449-2-git-send-email-zhang.chunyan@linaro.org
State New
Headers show
Series
  • Add support for using external dma in SDHCI
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Commit Message

Chunyan Zhang Nov. 12, 2018, 7:26 a.m.
Some standard SD host controllers can support both external dma
controllers as well as ADMA/SDMA in which the SD host controller
acts as DMA master. TI's omap controller is the case as an example.

Currently the generic SDHCI code supports ADMA/SDMA integrated in
the host controller but does not have any support for external DMA
controllers implemented using dmaengine, meaning that custom code is
needed for any systems that use an external DMA controller with SDHCI.

Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

---
 drivers/mmc/host/Kconfig |  13 ++++
 drivers/mmc/host/sdhci.c | 181 ++++++++++++++++++++++++++++++++++++++++++++++-
 drivers/mmc/host/sdhci.h |   8 +++
 3 files changed, 201 insertions(+), 1 deletion(-)

-- 
2.7.4

Comments

Adrian Hunter Nov. 20, 2018, 1:39 p.m. | #1
On 12/11/18 9:26 AM, Chunyan Zhang wrote:
> Some standard SD host controllers can support both external dma

> controllers as well as ADMA/SDMA in which the SD host controller

> acts as DMA master. TI's omap controller is the case as an example.

> 

> Currently the generic SDHCI code supports ADMA/SDMA integrated in

> the host controller but does not have any support for external DMA

> controllers implemented using dmaengine, meaning that custom code is

> needed for any systems that use an external DMA controller with SDHCI.


I still think you probably need to reset the DMA if there are transfer
errors - perhaps you could comment on that.  Also there are some comments below.

> 

> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

> ---

>  drivers/mmc/host/Kconfig |  13 ++++

>  drivers/mmc/host/sdhci.c | 181 ++++++++++++++++++++++++++++++++++++++++++++++-

>  drivers/mmc/host/sdhci.h |   8 +++

>  3 files changed, 201 insertions(+), 1 deletion(-)

> 

> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

> index 1b58739..7bf3eff 100644

> --- a/drivers/mmc/host/Kconfig

> +++ b/drivers/mmc/host/Kconfig

> @@ -977,3 +977,16 @@ config MMC_SDHCI_OMAP

>  	  If you have a controller with this interface, say Y or M here.

>  

>  	  If unsure, say N.

> +

> +config MMC_SDHCI_EXTERNAL_DMA

> +        bool "Support external DMA in standard SD host controller"


It would be simpler if the drivers that needed it just selected it e.g.

config MMC_SDHCI_OMAP
	tristate "TI SDHCI Controller Support"
	depends on MMC_SDHCI_PLTFM && OF
	select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE

> +	depends on MMC_SDHCI

> +	depends on DMA_ENGINE

> +	help

> +	  This is an option for using external DMA device via dmaengine

> +	  framework.

> +

> +	  If you have a controller which support using external DMA device

> +	  for data transfer, can say Y.

> +

> +	  If unsure, say N.

> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c

> index 99bdae5..853cc98 100644

> --- a/drivers/mmc/host/sdhci.c

> +++ b/drivers/mmc/host/sdhci.c

> @@ -14,6 +14,7 @@

>   */

>  

>  #include <linux/delay.h>

> +#include <linux/dmaengine.h>

>  #include <linux/ktime.h>

>  #include <linux/highmem.h>

>  #include <linux/io.h>

> @@ -1309,6 +1310,158 @@ static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)

>  		del_timer(&host->timer);

>  }

>  

> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

> +static int sdhci_external_dma_init(struct sdhci_host *host)

> +{

> +	int ret = 0;

> +	struct mmc_host *mmc = host->mmc;

> +

> +	host->tx_chan = dma_request_chan(mmc->parent, "tx");

> +	if (IS_ERR(host->tx_chan)) {

> +		ret = PTR_ERR(host->tx_chan);

> +		if (ret != -EPROBE_DEFER)

> +			pr_warn("Failed to request TX DMA channel.\n");

> +		host->tx_chan = NULL;

> +		return ret;

> +	}

> +

> +	host->rx_chan = dma_request_chan(mmc->parent, "rx");

> +	if (IS_ERR(host->rx_chan)) {

> +		if (host->tx_chan) {

> +			dma_release_channel(host->tx_chan);

> +			host->tx_chan = NULL;

> +		}

> +

> +		ret = PTR_ERR(host->rx_chan);

> +		if (ret != -EPROBE_DEFER)

> +			pr_warn("Failed to request RX DMA channel.\n");

> +		host->rx_chan = NULL;

> +	}

> +

> +	return ret;

> +}

> +

> +static inline struct dma_chan *

> +sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)

> +{

> +	return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;

> +}

> +

> +static int sdhci_external_dma_setup(struct sdhci_host *host,

> +				    struct mmc_command *cmd)

> +{

> +	int ret = 0, i;

> +	struct dma_async_tx_descriptor *desc;

> +	struct mmc_data *data = cmd->data;


cmd->data might be NULL?  Have you tested this?

> +	struct dma_chan *chan;

> +	struct dma_slave_config cfg;

> +	dma_cookie_t cookie;

> +

> +	if (!host->mapbase)

> +		return -EINVAL;

> +

> +	cfg.src_addr = host->mapbase + SDHCI_BUFFER;

> +	cfg.dst_addr = host->mapbase + SDHCI_BUFFER;

> +	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> +	cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> +	cfg.src_maxburst = data->blksz / 4;

> +	cfg.dst_maxburst = data->blksz / 4;

> +

> +	/* Sanity check: all the SG entries must be aligned by block size. */

> +	for (i = 0; i < data->sg_len; i++) {

> +		if ((data->sg + i)->length % data->blksz)

> +			return -EINVAL;

> +	}

> +

> +	chan = sdhci_external_dma_channel(host, data);

> +

> +	ret = dmaengine_slave_config(chan, &cfg);

> +	if (ret)

> +		return ret;

> +

> +	desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,

> +				       mmc_get_dma_dir(data),

> +				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

> +	if (!desc)

> +		return -EINVAL;

> +

> +	desc->callback = NULL;

> +	desc->callback_param = NULL;

> +

> +	cookie = dmaengine_submit(desc);

> +	if (cookie < 0)

> +		ret = cookie;

> +

> +	return ret;

> +}

> +

> +static void sdhci_external_dma_release(struct sdhci_host *host)

> +{

> +	if (host->tx_chan) {

> +		dma_release_channel(host->tx_chan);

> +		host->tx_chan = NULL;

> +	}

> +

> +	if (host->rx_chan) {

> +		dma_release_channel(host->rx_chan);

> +		host->rx_chan = NULL;

> +	}

> +

> +	sdhci_switch_external_dma(host, false);

> +}

> +

> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{

> +	if (sdhci_external_dma_setup(host, cmd)) {

> +		sdhci_external_dma_release(host);

> +		pr_err("%s: Failed to setup external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",

> +		       mmc_hostname(host->mmc));

> +	} else {

> +		/* Prepare for using external dma */

> +		host->flags |= SDHCI_REQ_USE_DMA;

> +	}

> +

> +	sdhci_prepare_data(host, cmd);

> +}

> +

> +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{

> +	struct dma_chan *chan = sdhci_external_dma_channel(host, cmd->data);


cmd->data might be NULL?  Have you tested this?

> +

> +	if (cmd->opcode != MMC_SET_BLOCK_COUNT) {


I would have thought:

	if (cmd->data)

> +		sdhci_set_timeout(host, cmd);

> +		dma_async_issue_pending(chan);

> +	}

> +}

> +#else

> +static int sdhci_external_dma_init(struct sdhci_host *host)

> +{

> +	return 0;


That should return an error, perhaps -EOPNOTSUPP.

> +}

> +

> +static void sdhci_external_dma_release(struct sdhci_host *host)

> +{}

> +

> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{

> +	/* If SDHCI_EXTDMA not supported, PIO will be used */


SDHCI_EXTDMA is now MMC_SDHCI_EXTERNAL_DMA

> +	sdhci_prepare_data(host, cmd);

> +}

> +

> +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{}

> +#endif

> +

> +void sdhci_switch_external_dma(struct sdhci_host *host, bool en)

> +{

> +	host->use_external_dma = en;

> +}

> +EXPORT_SYMBOL_GPL(sdhci_switch_external_dma);

> +

>  void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>  {

>  	int flags;

> @@ -1355,7 +1508,10 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>  		host->data_cmd = cmd;

>  	}

>  

> -	sdhci_prepare_data(host, cmd);

> +	if (host->use_external_dma)

> +		sdhci_external_dma_prepare_data(host, cmd);

> +	else

> +		sdhci_prepare_data(host, cmd);

>  

>  	sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);

>  

> @@ -1397,6 +1553,9 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>  		timeout += 10 * HZ;

>  	sdhci_mod_timer(host, cmd->mrq, timeout);

>  

> +	if (host->use_external_dma)

> +		sdhci_external_dma_pre_transfer(host, cmd);

> +

>  	sdhci_writew(host, SDHCI_MAKE_CMD(cmd->opcode, flags), SDHCI_COMMAND);

>  }

>  EXPORT_SYMBOL_GPL(sdhci_send_command);

> @@ -4133,6 +4292,19 @@ int sdhci_setup_host(struct sdhci_host *host)

>  			return ret;

>  	}

>  

> +	if (host->use_external_dma) {

> +		ret = sdhci_external_dma_init(host);

> +		if (ret == -EPROBE_DEFER)

> +			goto unreg;

> +

> +		/*

> +		 * Fall back to use the DMA/PIO integrated in standard SDHCI

> +		 * instead of external DMA devices.

> +		 */

> +		if (ret)

> +			sdhci_switch_external_dma(host, false);

> +	}

> +

>  	return 0;

>  

>  unreg:

> @@ -4161,6 +4333,10 @@ void sdhci_cleanup_host(struct sdhci_host *host)

>  		dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz +

>  				  host->adma_table_sz, host->align_buffer,

>  				  host->align_addr);

> +

> +	if (host->use_external_dma)

> +		sdhci_external_dma_release(host);

> +

>  	host->adma_table = NULL;

>  	host->align_buffer = NULL;

>  }

> @@ -4295,6 +4471,9 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)

>  				  host->adma_table_sz, host->align_buffer,

>  				  host->align_addr);

>  

> +	if (host->use_external_dma)

> +		sdhci_external_dma_release(host);

> +

>  	host->adma_table = NULL;

>  	host->align_buffer = NULL;

>  }

> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h

> index b001cf4..8e50a97 100644

> --- a/drivers/mmc/host/sdhci.h

> +++ b/drivers/mmc/host/sdhci.h

> @@ -475,6 +475,7 @@ struct sdhci_host {

>  

>  	int irq;		/* Device IRQ */

>  	void __iomem *ioaddr;	/* Mapped address */

> +	phys_addr_t mapbase;	/* physical address base */

>  	char *bounce_buffer;	/* For packing SDMA reads/writes */

>  	dma_addr_t bounce_addr;

>  	unsigned int bounce_buffer_size;

> @@ -524,6 +525,7 @@ struct sdhci_host {

>  	bool pending_reset;	/* Cmd/data reset is pending */

>  	bool irq_wake_enabled;	/* IRQ wakeup is enabled */

>  	bool v4_mode;		/* Host Version 4 Enable */

> +	bool use_external_dma;

>  

>  	struct mmc_request *mrqs_done[SDHCI_MAX_MRQS];	/* Requests done */

>  	struct mmc_command *cmd;	/* Current command */

> @@ -552,6 +554,11 @@ struct sdhci_host {

>  	struct timer_list timer;	/* Timer for timeouts */

>  	struct timer_list data_timer;	/* Timer for data timeouts */

>  

> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

> +	struct dma_chan	*rx_chan;

> +	struct dma_chan	*tx_chan;

> +#endif

> +

>  	u32 caps;		/* CAPABILITY_0 */

>  	u32 caps1;		/* CAPABILITY_1 */

>  	bool read_caps;		/* Capability flags have been read */

> @@ -785,5 +792,6 @@ void sdhci_start_tuning(struct sdhci_host *host);

>  void sdhci_end_tuning(struct sdhci_host *host);

>  void sdhci_reset_tuning(struct sdhci_host *host);

>  void sdhci_send_tuning(struct sdhci_host *host, u32 opcode);

> +void sdhci_switch_external_dma(struct sdhci_host *host, bool en);

>  

>  #endif /* __SDHCI_HW_H */

>
Chunyan Zhang Nov. 29, 2018, 6:22 a.m. | #2
On Tue, 20 Nov 2018 at 21:41, Adrian Hunter <adrian.hunter@intel.com> wrote:
>

> On 12/11/18 9:26 AM, Chunyan Zhang wrote:

> > Some standard SD host controllers can support both external dma

> > controllers as well as ADMA/SDMA in which the SD host controller

> > acts as DMA master. TI's omap controller is the case as an example.

> >

> > Currently the generic SDHCI code supports ADMA/SDMA integrated in

> > the host controller but does not have any support for external DMA

> > controllers implemented using dmaengine, meaning that custom code is

> > needed for any systems that use an external DMA controller with SDHCI.

>

> I still think you probably need to reset the DMA if there are transfer

> errors - perhaps you could comment on that.  Also there are some comments below.


With regard to "transfer error", do you mean if
sdhci_external_dma_setup() failed?

Thanks,
Chunyan


>

> >

> > Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

> > ---

> >  drivers/mmc/host/Kconfig |  13 ++++

> >  drivers/mmc/host/sdhci.c | 181 ++++++++++++++++++++++++++++++++++++++++++++++-

> >  drivers/mmc/host/sdhci.h |   8 +++

> >  3 files changed, 201 insertions(+), 1 deletion(-)

> >

> > diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

> > index 1b58739..7bf3eff 100644

> > --- a/drivers/mmc/host/Kconfig

> > +++ b/drivers/mmc/host/Kconfig

> > @@ -977,3 +977,16 @@ config MMC_SDHCI_OMAP

> >         If you have a controller with this interface, say Y or M here.

> >

> >         If unsure, say N.

> > +

> > +config MMC_SDHCI_EXTERNAL_DMA

> > +        bool "Support external DMA in standard SD host controller"

>

> It would be simpler if the drivers that needed it just selected it e.g.

>

> config MMC_SDHCI_OMAP

>         tristate "TI SDHCI Controller Support"

>         depends on MMC_SDHCI_PLTFM && OF

>         select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE

>

> > +     depends on MMC_SDHCI

> > +     depends on DMA_ENGINE

> > +     help

> > +       This is an option for using external DMA device via dmaengine

> > +       framework.

> > +

> > +       If you have a controller which support using external DMA device

> > +       for data transfer, can say Y.

> > +

> > +       If unsure, say N.

> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c

> > index 99bdae5..853cc98 100644

> > --- a/drivers/mmc/host/sdhci.c

> > +++ b/drivers/mmc/host/sdhci.c

> > @@ -14,6 +14,7 @@

> >   */

> >

> >  #include <linux/delay.h>

> > +#include <linux/dmaengine.h>

> >  #include <linux/ktime.h>

> >  #include <linux/highmem.h>

> >  #include <linux/io.h>

> > @@ -1309,6 +1310,158 @@ static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)

> >               del_timer(&host->timer);

> >  }

> >

> > +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

> > +static int sdhci_external_dma_init(struct sdhci_host *host)

> > +{

> > +     int ret = 0;

> > +     struct mmc_host *mmc = host->mmc;

> > +

> > +     host->tx_chan = dma_request_chan(mmc->parent, "tx");

> > +     if (IS_ERR(host->tx_chan)) {

> > +             ret = PTR_ERR(host->tx_chan);

> > +             if (ret != -EPROBE_DEFER)

> > +                     pr_warn("Failed to request TX DMA channel.\n");

> > +             host->tx_chan = NULL;

> > +             return ret;

> > +     }

> > +

> > +     host->rx_chan = dma_request_chan(mmc->parent, "rx");

> > +     if (IS_ERR(host->rx_chan)) {

> > +             if (host->tx_chan) {

> > +                     dma_release_channel(host->tx_chan);

> > +                     host->tx_chan = NULL;

> > +             }

> > +

> > +             ret = PTR_ERR(host->rx_chan);

> > +             if (ret != -EPROBE_DEFER)

> > +                     pr_warn("Failed to request RX DMA channel.\n");

> > +             host->rx_chan = NULL;

> > +     }

> > +

> > +     return ret;

> > +}

> > +

> > +static inline struct dma_chan *

> > +sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)

> > +{

> > +     return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;

> > +}

> > +

> > +static int sdhci_external_dma_setup(struct sdhci_host *host,

> > +                                 struct mmc_command *cmd)

> > +{

> > +     int ret = 0, i;

> > +     struct dma_async_tx_descriptor *desc;

> > +     struct mmc_data *data = cmd->data;

>

> cmd->data might be NULL?  Have you tested this?

>

> > +     struct dma_chan *chan;

> > +     struct dma_slave_config cfg;

> > +     dma_cookie_t cookie;

> > +

> > +     if (!host->mapbase)

> > +             return -EINVAL;

> > +

> > +     cfg.src_addr = host->mapbase + SDHCI_BUFFER;

> > +     cfg.dst_addr = host->mapbase + SDHCI_BUFFER;

> > +     cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> > +     cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> > +     cfg.src_maxburst = data->blksz / 4;

> > +     cfg.dst_maxburst = data->blksz / 4;

> > +

> > +     /* Sanity check: all the SG entries must be aligned by block size. */

> > +     for (i = 0; i < data->sg_len; i++) {

> > +             if ((data->sg + i)->length % data->blksz)

> > +                     return -EINVAL;

> > +     }

> > +

> > +     chan = sdhci_external_dma_channel(host, data);

> > +

> > +     ret = dmaengine_slave_config(chan, &cfg);

> > +     if (ret)

> > +             return ret;

> > +

> > +     desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,

> > +                                    mmc_get_dma_dir(data),

> > +                                    DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

> > +     if (!desc)

> > +             return -EINVAL;

> > +

> > +     desc->callback = NULL;

> > +     desc->callback_param = NULL;

> > +

> > +     cookie = dmaengine_submit(desc);

> > +     if (cookie < 0)

> > +             ret = cookie;

> > +

> > +     return ret;

> > +}

> > +

> > +static void sdhci_external_dma_release(struct sdhci_host *host)

> > +{

> > +     if (host->tx_chan) {

> > +             dma_release_channel(host->tx_chan);

> > +             host->tx_chan = NULL;

> > +     }

> > +

> > +     if (host->rx_chan) {

> > +             dma_release_channel(host->rx_chan);

> > +             host->rx_chan = NULL;

> > +     }

> > +

> > +     sdhci_switch_external_dma(host, false);

> > +}

> > +

> > +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> > +                                         struct mmc_command *cmd)

> > +{

> > +     if (sdhci_external_dma_setup(host, cmd)) {

> > +             sdhci_external_dma_release(host);

> > +             pr_err("%s: Failed to setup external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",

> > +                    mmc_hostname(host->mmc));

> > +     } else {

> > +             /* Prepare for using external dma */

> > +             host->flags |= SDHCI_REQ_USE_DMA;

> > +     }

> > +

> > +     sdhci_prepare_data(host, cmd);

> > +}

> > +

> > +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

> > +                                         struct mmc_command *cmd)

> > +{

> > +     struct dma_chan *chan = sdhci_external_dma_channel(host, cmd->data);

>

> cmd->data might be NULL?  Have you tested this?

>

> > +

> > +     if (cmd->opcode != MMC_SET_BLOCK_COUNT) {

>

> I would have thought:

>

>         if (cmd->data)

>

> > +             sdhci_set_timeout(host, cmd);

> > +             dma_async_issue_pending(chan);

> > +     }

> > +}

> > +#else

> > +static int sdhci_external_dma_init(struct sdhci_host *host)

> > +{

> > +     return 0;

>

> That should return an error, perhaps -EOPNOTSUPP.

>

> > +}

> > +

> > +static void sdhci_external_dma_release(struct sdhci_host *host)

> > +{}

> > +

> > +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> > +                                         struct mmc_command *cmd)

> > +{

> > +     /* If SDHCI_EXTDMA not supported, PIO will be used */

>

> SDHCI_EXTDMA is now MMC_SDHCI_EXTERNAL_DMA

>

> > +     sdhci_prepare_data(host, cmd);

> > +}

> > +

> > +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

> > +                                         struct mmc_command *cmd)

> > +{}

> > +#endif

> > +

> > +void sdhci_switch_external_dma(struct sdhci_host *host, bool en)

> > +{

> > +     host->use_external_dma = en;

> > +}

> > +EXPORT_SYMBOL_GPL(sdhci_switch_external_dma);

> > +

> >  void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

> >  {

> >       int flags;

> > @@ -1355,7 +1508,10 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

> >               host->data_cmd = cmd;

> >       }

> >

> > -     sdhci_prepare_data(host, cmd);

> > +     if (host->use_external_dma)

> > +             sdhci_external_dma_prepare_data(host, cmd);

> > +     else

> > +             sdhci_prepare_data(host, cmd);

> >

> >       sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);

> >

> > @@ -1397,6 +1553,9 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

> >               timeout += 10 * HZ;

> >       sdhci_mod_timer(host, cmd->mrq, timeout);

> >

> > +     if (host->use_external_dma)

> > +             sdhci_external_dma_pre_transfer(host, cmd);

> > +

> >       sdhci_writew(host, SDHCI_MAKE_CMD(cmd->opcode, flags), SDHCI_COMMAND);

> >  }

> >  EXPORT_SYMBOL_GPL(sdhci_send_command);

> > @@ -4133,6 +4292,19 @@ int sdhci_setup_host(struct sdhci_host *host)

> >                       return ret;

> >       }

> >

> > +     if (host->use_external_dma) {

> > +             ret = sdhci_external_dma_init(host);

> > +             if (ret == -EPROBE_DEFER)

> > +                     goto unreg;

> > +

> > +             /*

> > +              * Fall back to use the DMA/PIO integrated in standard SDHCI

> > +              * instead of external DMA devices.

> > +              */

> > +             if (ret)

> > +                     sdhci_switch_external_dma(host, false);

> > +     }

> > +

> >       return 0;

> >

> >  unreg:

> > @@ -4161,6 +4333,10 @@ void sdhci_cleanup_host(struct sdhci_host *host)

> >               dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz +

> >                                 host->adma_table_sz, host->align_buffer,

> >                                 host->align_addr);

> > +

> > +     if (host->use_external_dma)

> > +             sdhci_external_dma_release(host);

> > +

> >       host->adma_table = NULL;

> >       host->align_buffer = NULL;

> >  }

> > @@ -4295,6 +4471,9 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)

> >                                 host->adma_table_sz, host->align_buffer,

> >                                 host->align_addr);

> >

> > +     if (host->use_external_dma)

> > +             sdhci_external_dma_release(host);

> > +

> >       host->adma_table = NULL;

> >       host->align_buffer = NULL;

> >  }

> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h

> > index b001cf4..8e50a97 100644

> > --- a/drivers/mmc/host/sdhci.h

> > +++ b/drivers/mmc/host/sdhci.h

> > @@ -475,6 +475,7 @@ struct sdhci_host {

> >

> >       int irq;                /* Device IRQ */

> >       void __iomem *ioaddr;   /* Mapped address */

> > +     phys_addr_t mapbase;    /* physical address base */

> >       char *bounce_buffer;    /* For packing SDMA reads/writes */

> >       dma_addr_t bounce_addr;

> >       unsigned int bounce_buffer_size;

> > @@ -524,6 +525,7 @@ struct sdhci_host {

> >       bool pending_reset;     /* Cmd/data reset is pending */

> >       bool irq_wake_enabled;  /* IRQ wakeup is enabled */

> >       bool v4_mode;           /* Host Version 4 Enable */

> > +     bool use_external_dma;

> >

> >       struct mmc_request *mrqs_done[SDHCI_MAX_MRQS];  /* Requests done */

> >       struct mmc_command *cmd;        /* Current command */

> > @@ -552,6 +554,11 @@ struct sdhci_host {

> >       struct timer_list timer;        /* Timer for timeouts */

> >       struct timer_list data_timer;   /* Timer for data timeouts */

> >

> > +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

> > +     struct dma_chan *rx_chan;

> > +     struct dma_chan *tx_chan;

> > +#endif

> > +

> >       u32 caps;               /* CAPABILITY_0 */

> >       u32 caps1;              /* CAPABILITY_1 */

> >       bool read_caps;         /* Capability flags have been read */

> > @@ -785,5 +792,6 @@ void sdhci_start_tuning(struct sdhci_host *host);

> >  void sdhci_end_tuning(struct sdhci_host *host);

> >  void sdhci_reset_tuning(struct sdhci_host *host);

> >  void sdhci_send_tuning(struct sdhci_host *host, u32 opcode);

> > +void sdhci_switch_external_dma(struct sdhci_host *host, bool en);

> >

> >  #endif /* __SDHCI_HW_H */

> >

>
Adrian Hunter Nov. 29, 2018, 7:35 a.m. | #3
On 29/11/18 8:22 AM, Chunyan Zhang wrote:
> On Tue, 20 Nov 2018 at 21:41, Adrian Hunter <adrian.hunter@intel.com> wrote:

>>

>> On 12/11/18 9:26 AM, Chunyan Zhang wrote:

>>> Some standard SD host controllers can support both external dma

>>> controllers as well as ADMA/SDMA in which the SD host controller

>>> acts as DMA master. TI's omap controller is the case as an example.

>>>

>>> Currently the generic SDHCI code supports ADMA/SDMA integrated in

>>> the host controller but does not have any support for external DMA

>>> controllers implemented using dmaengine, meaning that custom code is

>>> needed for any systems that use an external DMA controller with SDHCI.

>>

>> I still think you probably need to reset the DMA if there are transfer

>> errors - perhaps you could comment on that.  Also there are some comments below.

> 

> With regard to "transfer error", do you mean if

> sdhci_external_dma_setup() failed?


No, I mean any error interrupt that can leave the DMA uncompleted.  For
SDHCI, resetting the data circuit cleans that up, but presumably something
is needed for external DMA?

> 

> Thanks,

> Chunyan

> 

> 

>>

>>>

>>> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

>>> ---

>>>  drivers/mmc/host/Kconfig |  13 ++++

>>>  drivers/mmc/host/sdhci.c | 181 ++++++++++++++++++++++++++++++++++++++++++++++-

>>>  drivers/mmc/host/sdhci.h |   8 +++

>>>  3 files changed, 201 insertions(+), 1 deletion(-)

>>>

>>> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

>>> index 1b58739..7bf3eff 100644

>>> --- a/drivers/mmc/host/Kconfig

>>> +++ b/drivers/mmc/host/Kconfig

>>> @@ -977,3 +977,16 @@ config MMC_SDHCI_OMAP

>>>         If you have a controller with this interface, say Y or M here.

>>>

>>>         If unsure, say N.

>>> +

>>> +config MMC_SDHCI_EXTERNAL_DMA

>>> +        bool "Support external DMA in standard SD host controller"

>>

>> It would be simpler if the drivers that needed it just selected it e.g.

>>

>> config MMC_SDHCI_OMAP

>>         tristate "TI SDHCI Controller Support"

>>         depends on MMC_SDHCI_PLTFM && OF

>>         select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE

>>

>>> +     depends on MMC_SDHCI

>>> +     depends on DMA_ENGINE

>>> +     help

>>> +       This is an option for using external DMA device via dmaengine

>>> +       framework.

>>> +

>>> +       If you have a controller which support using external DMA device

>>> +       for data transfer, can say Y.

>>> +

>>> +       If unsure, say N.

>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c

>>> index 99bdae5..853cc98 100644

>>> --- a/drivers/mmc/host/sdhci.c

>>> +++ b/drivers/mmc/host/sdhci.c

>>> @@ -14,6 +14,7 @@

>>>   */

>>>

>>>  #include <linux/delay.h>

>>> +#include <linux/dmaengine.h>

>>>  #include <linux/ktime.h>

>>>  #include <linux/highmem.h>

>>>  #include <linux/io.h>

>>> @@ -1309,6 +1310,158 @@ static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)

>>>               del_timer(&host->timer);

>>>  }

>>>

>>> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

>>> +static int sdhci_external_dma_init(struct sdhci_host *host)

>>> +{

>>> +     int ret = 0;

>>> +     struct mmc_host *mmc = host->mmc;

>>> +

>>> +     host->tx_chan = dma_request_chan(mmc->parent, "tx");

>>> +     if (IS_ERR(host->tx_chan)) {

>>> +             ret = PTR_ERR(host->tx_chan);

>>> +             if (ret != -EPROBE_DEFER)

>>> +                     pr_warn("Failed to request TX DMA channel.\n");

>>> +             host->tx_chan = NULL;

>>> +             return ret;

>>> +     }

>>> +

>>> +     host->rx_chan = dma_request_chan(mmc->parent, "rx");

>>> +     if (IS_ERR(host->rx_chan)) {

>>> +             if (host->tx_chan) {

>>> +                     dma_release_channel(host->tx_chan);

>>> +                     host->tx_chan = NULL;

>>> +             }

>>> +

>>> +             ret = PTR_ERR(host->rx_chan);

>>> +             if (ret != -EPROBE_DEFER)

>>> +                     pr_warn("Failed to request RX DMA channel.\n");

>>> +             host->rx_chan = NULL;

>>> +     }

>>> +

>>> +     return ret;

>>> +}

>>> +

>>> +static inline struct dma_chan *

>>> +sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)

>>> +{

>>> +     return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;

>>> +}

>>> +

>>> +static int sdhci_external_dma_setup(struct sdhci_host *host,

>>> +                                 struct mmc_command *cmd)

>>> +{

>>> +     int ret = 0, i;

>>> +     struct dma_async_tx_descriptor *desc;

>>> +     struct mmc_data *data = cmd->data;

>>

>> cmd->data might be NULL?  Have you tested this?

>>

>>> +     struct dma_chan *chan;

>>> +     struct dma_slave_config cfg;

>>> +     dma_cookie_t cookie;

>>> +

>>> +     if (!host->mapbase)

>>> +             return -EINVAL;

>>> +

>>> +     cfg.src_addr = host->mapbase + SDHCI_BUFFER;

>>> +     cfg.dst_addr = host->mapbase + SDHCI_BUFFER;

>>> +     cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

>>> +     cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

>>> +     cfg.src_maxburst = data->blksz / 4;

>>> +     cfg.dst_maxburst = data->blksz / 4;

>>> +

>>> +     /* Sanity check: all the SG entries must be aligned by block size. */

>>> +     for (i = 0; i < data->sg_len; i++) {

>>> +             if ((data->sg + i)->length % data->blksz)

>>> +                     return -EINVAL;

>>> +     }

>>> +

>>> +     chan = sdhci_external_dma_channel(host, data);

>>> +

>>> +     ret = dmaengine_slave_config(chan, &cfg);

>>> +     if (ret)

>>> +             return ret;

>>> +

>>> +     desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,

>>> +                                    mmc_get_dma_dir(data),

>>> +                                    DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

>>> +     if (!desc)

>>> +             return -EINVAL;

>>> +

>>> +     desc->callback = NULL;

>>> +     desc->callback_param = NULL;

>>> +

>>> +     cookie = dmaengine_submit(desc);

>>> +     if (cookie < 0)

>>> +             ret = cookie;

>>> +

>>> +     return ret;

>>> +}

>>> +

>>> +static void sdhci_external_dma_release(struct sdhci_host *host)

>>> +{

>>> +     if (host->tx_chan) {

>>> +             dma_release_channel(host->tx_chan);

>>> +             host->tx_chan = NULL;

>>> +     }

>>> +

>>> +     if (host->rx_chan) {

>>> +             dma_release_channel(host->rx_chan);

>>> +             host->rx_chan = NULL;

>>> +     }

>>> +

>>> +     sdhci_switch_external_dma(host, false);

>>> +}

>>> +

>>> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

>>> +                                         struct mmc_command *cmd)

>>> +{

>>> +     if (sdhci_external_dma_setup(host, cmd)) {

>>> +             sdhci_external_dma_release(host);

>>> +             pr_err("%s: Failed to setup external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",

>>> +                    mmc_hostname(host->mmc));

>>> +     } else {

>>> +             /* Prepare for using external dma */

>>> +             host->flags |= SDHCI_REQ_USE_DMA;

>>> +     }

>>> +

>>> +     sdhci_prepare_data(host, cmd);

>>> +}

>>> +

>>> +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

>>> +                                         struct mmc_command *cmd)

>>> +{

>>> +     struct dma_chan *chan = sdhci_external_dma_channel(host, cmd->data);

>>

>> cmd->data might be NULL?  Have you tested this?

>>

>>> +

>>> +     if (cmd->opcode != MMC_SET_BLOCK_COUNT) {

>>

>> I would have thought:

>>

>>         if (cmd->data)

>>

>>> +             sdhci_set_timeout(host, cmd);

>>> +             dma_async_issue_pending(chan);

>>> +     }

>>> +}

>>> +#else

>>> +static int sdhci_external_dma_init(struct sdhci_host *host)

>>> +{

>>> +     return 0;

>>

>> That should return an error, perhaps -EOPNOTSUPP.

>>

>>> +}

>>> +

>>> +static void sdhci_external_dma_release(struct sdhci_host *host)

>>> +{}

>>> +

>>> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

>>> +                                         struct mmc_command *cmd)

>>> +{

>>> +     /* If SDHCI_EXTDMA not supported, PIO will be used */

>>

>> SDHCI_EXTDMA is now MMC_SDHCI_EXTERNAL_DMA

>>

>>> +     sdhci_prepare_data(host, cmd);

>>> +}

>>> +

>>> +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

>>> +                                         struct mmc_command *cmd)

>>> +{}

>>> +#endif

>>> +

>>> +void sdhci_switch_external_dma(struct sdhci_host *host, bool en)

>>> +{

>>> +     host->use_external_dma = en;

>>> +}

>>> +EXPORT_SYMBOL_GPL(sdhci_switch_external_dma);

>>> +

>>>  void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>>>  {

>>>       int flags;

>>> @@ -1355,7 +1508,10 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>>>               host->data_cmd = cmd;

>>>       }

>>>

>>> -     sdhci_prepare_data(host, cmd);

>>> +     if (host->use_external_dma)

>>> +             sdhci_external_dma_prepare_data(host, cmd);

>>> +     else

>>> +             sdhci_prepare_data(host, cmd);

>>>

>>>       sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);

>>>

>>> @@ -1397,6 +1553,9 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>>>               timeout += 10 * HZ;

>>>       sdhci_mod_timer(host, cmd->mrq, timeout);

>>>

>>> +     if (host->use_external_dma)

>>> +             sdhci_external_dma_pre_transfer(host, cmd);

>>> +

>>>       sdhci_writew(host, SDHCI_MAKE_CMD(cmd->opcode, flags), SDHCI_COMMAND);

>>>  }

>>>  EXPORT_SYMBOL_GPL(sdhci_send_command);

>>> @@ -4133,6 +4292,19 @@ int sdhci_setup_host(struct sdhci_host *host)

>>>                       return ret;

>>>       }

>>>

>>> +     if (host->use_external_dma) {

>>> +             ret = sdhci_external_dma_init(host);

>>> +             if (ret == -EPROBE_DEFER)

>>> +                     goto unreg;

>>> +

>>> +             /*

>>> +              * Fall back to use the DMA/PIO integrated in standard SDHCI

>>> +              * instead of external DMA devices.

>>> +              */

>>> +             if (ret)

>>> +                     sdhci_switch_external_dma(host, false);

>>> +     }

>>> +

>>>       return 0;

>>>

>>>  unreg:

>>> @@ -4161,6 +4333,10 @@ void sdhci_cleanup_host(struct sdhci_host *host)

>>>               dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz +

>>>                                 host->adma_table_sz, host->align_buffer,

>>>                                 host->align_addr);

>>> +

>>> +     if (host->use_external_dma)

>>> +             sdhci_external_dma_release(host);

>>> +

>>>       host->adma_table = NULL;

>>>       host->align_buffer = NULL;

>>>  }

>>> @@ -4295,6 +4471,9 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)

>>>                                 host->adma_table_sz, host->align_buffer,

>>>                                 host->align_addr);

>>>

>>> +     if (host->use_external_dma)

>>> +             sdhci_external_dma_release(host);

>>> +

>>>       host->adma_table = NULL;

>>>       host->align_buffer = NULL;

>>>  }

>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h

>>> index b001cf4..8e50a97 100644

>>> --- a/drivers/mmc/host/sdhci.h

>>> +++ b/drivers/mmc/host/sdhci.h

>>> @@ -475,6 +475,7 @@ struct sdhci_host {

>>>

>>>       int irq;                /* Device IRQ */

>>>       void __iomem *ioaddr;   /* Mapped address */

>>> +     phys_addr_t mapbase;    /* physical address base */

>>>       char *bounce_buffer;    /* For packing SDMA reads/writes */

>>>       dma_addr_t bounce_addr;

>>>       unsigned int bounce_buffer_size;

>>> @@ -524,6 +525,7 @@ struct sdhci_host {

>>>       bool pending_reset;     /* Cmd/data reset is pending */

>>>       bool irq_wake_enabled;  /* IRQ wakeup is enabled */

>>>       bool v4_mode;           /* Host Version 4 Enable */

>>> +     bool use_external_dma;

>>>

>>>       struct mmc_request *mrqs_done[SDHCI_MAX_MRQS];  /* Requests done */

>>>       struct mmc_command *cmd;        /* Current command */

>>> @@ -552,6 +554,11 @@ struct sdhci_host {

>>>       struct timer_list timer;        /* Timer for timeouts */

>>>       struct timer_list data_timer;   /* Timer for data timeouts */

>>>

>>> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

>>> +     struct dma_chan *rx_chan;

>>> +     struct dma_chan *tx_chan;

>>> +#endif

>>> +

>>>       u32 caps;               /* CAPABILITY_0 */

>>>       u32 caps1;              /* CAPABILITY_1 */

>>>       bool read_caps;         /* Capability flags have been read */

>>> @@ -785,5 +792,6 @@ void sdhci_start_tuning(struct sdhci_host *host);

>>>  void sdhci_end_tuning(struct sdhci_host *host);

>>>  void sdhci_reset_tuning(struct sdhci_host *host);

>>>  void sdhci_send_tuning(struct sdhci_host *host, u32 opcode);

>>> +void sdhci_switch_external_dma(struct sdhci_host *host, bool en);

>>>

>>>  #endif /* __SDHCI_HW_H */

>>>

>>

>
Adrian Hunter Nov. 29, 2018, 9:23 a.m. | #4
On 29/11/18 8:07 AM, Chunyan Zhang wrote:
> Some standard SD host controllers can support both external dma

> controllers as well as ADMA/SDMA in which the SD host controller

> acts as DMA master. TI's omap controller is the case as an example.

> 

> Currently the generic SDHCI code supports ADMA/SDMA integrated in

> the host controller but does not have any support for external DMA

> controllers implemented using dmaengine, meaning that custom code is

> needed for any systems that use an external DMA controller with SDHCI.

> 

> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

> ---

>  drivers/mmc/host/Kconfig |  14 ++++

>  drivers/mmc/host/sdhci.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++-

>  drivers/mmc/host/sdhci.h |   8 ++

>  3 files changed, 206 insertions(+), 1 deletion(-)

> 

> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

> index 1b58739..4183f43 100644

> --- a/drivers/mmc/host/Kconfig

> +++ b/drivers/mmc/host/Kconfig

> @@ -969,6 +969,7 @@ config MMC_SDHCI_XENON

>  config MMC_SDHCI_OMAP

>  	tristate "TI SDHCI Controller Support"

>  	depends on MMC_SDHCI_PLTFM && OF

> +	select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE

>  	help

>  	  This selects the Secure Digital Host Controller Interface (SDHCI)

>  	  support present in TI's DRA7 SOCs. The controller supports

> @@ -977,3 +978,16 @@ config MMC_SDHCI_OMAP

>  	  If you have a controller with this interface, say Y or M here.

>  

>  	  If unsure, say N.

> +

> +config MMC_SDHCI_EXTERNAL_DMA

> +        bool "Support external DMA in standard SD host controller"

> +	depends on MMC_SDHCI

> +	depends on DMA_ENGINE

> +	help

> +	  This is an option for using external DMA device via dmaengine

> +	  framework.

> +

> +	  If you have a controller which support using external DMA device

> +	  for data transfer, can say Y.

> +

> +	  If unsure, say N.


So if you are going to select this, then you don't need the prompt or help
anymore i.e.

config MMC_SDHCI_EXTERNAL_DMA
	bool


> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c

> index 99bdae5..ad7cc80 100644

> --- a/drivers/mmc/host/sdhci.c

> +++ b/drivers/mmc/host/sdhci.c

> @@ -14,6 +14,7 @@

>   */

>  

>  #include <linux/delay.h>

> +#include <linux/dmaengine.h>

>  #include <linux/ktime.h>

>  #include <linux/highmem.h>

>  #include <linux/io.h>

> @@ -1309,6 +1310,162 @@ static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)

>  		del_timer(&host->timer);

>  }

>  

> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

> +static int sdhci_external_dma_init(struct sdhci_host *host)

> +{

> +	int ret = 0;

> +	struct mmc_host *mmc = host->mmc;

> +

> +	host->tx_chan = dma_request_chan(mmc->parent, "tx");

> +	if (IS_ERR(host->tx_chan)) {

> +		ret = PTR_ERR(host->tx_chan);

> +		if (ret != -EPROBE_DEFER)

> +			pr_warn("Failed to request TX DMA channel.\n");

> +		host->tx_chan = NULL;

> +		return ret;

> +	}

> +

> +	host->rx_chan = dma_request_chan(mmc->parent, "rx");

> +	if (IS_ERR(host->rx_chan)) {

> +		if (host->tx_chan) {

> +			dma_release_channel(host->tx_chan);

> +			host->tx_chan = NULL;

> +		}

> +

> +		ret = PTR_ERR(host->rx_chan);

> +		if (ret != -EPROBE_DEFER)

> +			pr_warn("Failed to request RX DMA channel.\n");

> +		host->rx_chan = NULL;

> +	}

> +

> +	return ret;

> +}

> +

> +static inline struct dma_chan *

> +sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)

> +{

> +	return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;

> +}

> +

> +static int sdhci_external_dma_setup(struct sdhci_host *host,

> +				    struct mmc_command *cmd)

> +{

> +	int ret, i;

> +	struct dma_async_tx_descriptor *desc;

> +	struct mmc_data *data = cmd->data;

> +	struct dma_chan *chan;

> +	struct dma_slave_config cfg;

> +	dma_cookie_t cookie;

> +

> +	if (!host->mapbase)

> +		return -EINVAL;

> +

> +	if (!data)

> +		return 0;


It would read better if the above 2 if-statements were the other way around i.e.

	if (!data)
		return 0;

	if (!host->mapbase)
		return -EINVAL;

> +

> +	cfg.src_addr = host->mapbase + SDHCI_BUFFER;

> +	cfg.dst_addr = host->mapbase + SDHCI_BUFFER;

> +	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> +	cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> +	cfg.src_maxburst = data->blksz / 4;

> +	cfg.dst_maxburst = data->blksz / 4;

> +

> +	/* Sanity check: all the SG entries must be aligned by block size. */

> +	for (i = 0; i < data->sg_len; i++) {

> +		if ((data->sg + i)->length % data->blksz)

> +			return -EINVAL;

> +	}

> +

> +	chan = sdhci_external_dma_channel(host, data);

> +

> +	ret = dmaengine_slave_config(chan, &cfg);

> +	if (ret)

> +		return ret;

> +

> +	desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,

> +				       mmc_get_dma_dir(data),

> +				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

> +	if (!desc)

> +		return -EINVAL;

> +

> +	desc->callback = NULL;

> +	desc->callback_param = NULL;

> +

> +	cookie = dmaengine_submit(desc);

> +	if (cookie < 0)

> +		ret = cookie;

> +

> +	return ret;

> +}

> +

> +static void sdhci_external_dma_release(struct sdhci_host *host)

> +{

> +	if (host->tx_chan) {

> +		dma_release_channel(host->tx_chan);

> +		host->tx_chan = NULL;

> +	}

> +

> +	if (host->rx_chan) {

> +		dma_release_channel(host->rx_chan);

> +		host->rx_chan = NULL;

> +	}

> +

> +	sdhci_switch_external_dma(host, false);

> +}

> +

> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{

> +	if (sdhci_external_dma_setup(host, cmd)) {

> +		sdhci_external_dma_release(host);

> +		pr_err("%s: Failed to setup external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",

> +		       mmc_hostname(host->mmc));

> +	} else {

> +		/* Prepare for using external dma */

> +		host->flags |= SDHCI_REQ_USE_DMA;

> +	}

> +

> +	sdhci_prepare_data(host, cmd);

> +}

> +

> +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{

> +	struct dma_chan *chan;

> +

> +	if (cmd->opcode != MMC_SET_BLOCK_COUNT && cmd->data) {


MMC_SET_BLOCK_COUNT doesn't have data so that part is not needed

> +		sdhci_set_timeout(host, cmd);

> +		chan = sdhci_external_dma_channel(host, cmd->data);

> +		dma_async_issue_pending(chan);

> +	}

> +}

> +#else

> +static int sdhci_external_dma_init(struct sdhci_host *host)

> +{

> +	return -EOPNOTSUPP;

> +}

> +

> +static void sdhci_external_dma_release(struct sdhci_host *host)

> +{}

> +

> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{

> +	/* If MMC_SDHCI_EXTERNAL_DMA not supported, PIO will be used */

> +	sdhci_prepare_data(host, cmd);

> +}

> +

> +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{}

> +#endif

> +

> +void sdhci_switch_external_dma(struct sdhci_host *host, bool en)

> +{

> +	host->use_external_dma = en;

> +}

> +EXPORT_SYMBOL_GPL(sdhci_switch_external_dma);

> +

>  void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>  {

>  	int flags;

> @@ -1355,7 +1512,10 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>  		host->data_cmd = cmd;

>  	}

>  

> -	sdhci_prepare_data(host, cmd);

> +	if (host->use_external_dma)

> +		sdhci_external_dma_prepare_data(host, cmd);

> +	else

> +		sdhci_prepare_data(host, cmd);

>  

>  	sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);

>  

> @@ -1397,6 +1557,9 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)

>  		timeout += 10 * HZ;

>  	sdhci_mod_timer(host, cmd->mrq, timeout);

>  

> +	if (host->use_external_dma)

> +		sdhci_external_dma_pre_transfer(host, cmd);

> +

>  	sdhci_writew(host, SDHCI_MAKE_CMD(cmd->opcode, flags), SDHCI_COMMAND);

>  }

>  EXPORT_SYMBOL_GPL(sdhci_send_command);

> @@ -4133,6 +4296,19 @@ int sdhci_setup_host(struct sdhci_host *host)

>  			return ret;

>  	}

>  

> +	if (host->use_external_dma) {

> +		ret = sdhci_external_dma_init(host);

> +		if (ret == -EPROBE_DEFER)

> +			goto unreg;

> +

> +		/*

> +		 * Fall back to use the DMA/PIO integrated in standard SDHCI

> +		 * instead of external DMA devices.

> +		 */

> +		if (ret)

> +			sdhci_switch_external_dma(host, false);

> +	}

> +

>  	return 0;

>  

>  unreg:

> @@ -4161,6 +4337,10 @@ void sdhci_cleanup_host(struct sdhci_host *host)

>  		dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz +

>  				  host->adma_table_sz, host->align_buffer,

>  				  host->align_addr);

> +

> +	if (host->use_external_dma)

> +		sdhci_external_dma_release(host);

> +

>  	host->adma_table = NULL;

>  	host->align_buffer = NULL;

>  }

> @@ -4295,6 +4475,9 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)

>  				  host->adma_table_sz, host->align_buffer,

>  				  host->align_addr);

>  

> +	if (host->use_external_dma)

> +		sdhci_external_dma_release(host);

> +

>  	host->adma_table = NULL;

>  	host->align_buffer = NULL;

>  }

> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h

> index b001cf4..8e50a97 100644

> --- a/drivers/mmc/host/sdhci.h

> +++ b/drivers/mmc/host/sdhci.h

> @@ -475,6 +475,7 @@ struct sdhci_host {

>  

>  	int irq;		/* Device IRQ */

>  	void __iomem *ioaddr;	/* Mapped address */

> +	phys_addr_t mapbase;	/* physical address base */

>  	char *bounce_buffer;	/* For packing SDMA reads/writes */

>  	dma_addr_t bounce_addr;

>  	unsigned int bounce_buffer_size;

> @@ -524,6 +525,7 @@ struct sdhci_host {

>  	bool pending_reset;	/* Cmd/data reset is pending */

>  	bool irq_wake_enabled;	/* IRQ wakeup is enabled */

>  	bool v4_mode;		/* Host Version 4 Enable */

> +	bool use_external_dma;

>  

>  	struct mmc_request *mrqs_done[SDHCI_MAX_MRQS];	/* Requests done */

>  	struct mmc_command *cmd;	/* Current command */

> @@ -552,6 +554,11 @@ struct sdhci_host {

>  	struct timer_list timer;	/* Timer for timeouts */

>  	struct timer_list data_timer;	/* Timer for data timeouts */

>  

> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

> +	struct dma_chan	*rx_chan;

> +	struct dma_chan	*tx_chan;

> +#endif

> +

>  	u32 caps;		/* CAPABILITY_0 */

>  	u32 caps1;		/* CAPABILITY_1 */

>  	bool read_caps;		/* Capability flags have been read */

> @@ -785,5 +792,6 @@ void sdhci_start_tuning(struct sdhci_host *host);

>  void sdhci_end_tuning(struct sdhci_host *host);

>  void sdhci_reset_tuning(struct sdhci_host *host);

>  void sdhci_send_tuning(struct sdhci_host *host, u32 opcode);

> +void sdhci_switch_external_dma(struct sdhci_host *host, bool en);

>  

>  #endif /* __SDHCI_HW_H */

>
Chunyan Zhang Nov. 29, 2018, 9:59 a.m. | #5
Hi Adrian,

On Thu, 29 Nov 2018 at 15:36, Adrian Hunter <adrian.hunter@intel.com> wrote:
>

> On 29/11/18 8:22 AM, Chunyan Zhang wrote:

> > On Tue, 20 Nov 2018 at 21:41, Adrian Hunter <adrian.hunter@intel.com> wrote:

> >>

> >> On 12/11/18 9:26 AM, Chunyan Zhang wrote:

> >>> Some standard SD host controllers can support both external dma

> >>> controllers as well as ADMA/SDMA in which the SD host controller

> >>> acts as DMA master. TI's omap controller is the case as an example.

> >>>

> >>> Currently the generic SDHCI code supports ADMA/SDMA integrated in

> >>> the host controller but does not have any support for external DMA

> >>> controllers implemented using dmaengine, meaning that custom code is

> >>> needed for any systems that use an external DMA controller with SDHCI.

> >>

> >> I still think you probably need to reset the DMA if there are transfer

> >> errors - perhaps you could comment on that.  Also there are some comments below.

> >

> > With regard to "transfer error", do you mean if

> > sdhci_external_dma_setup() failed?

>

> No, I mean any error interrupt that can leave the DMA uncompleted.  For

> SDHCI, resetting the data circuit cleans that up, but presumably something

> is needed for external DMA?


Yes, it should need a dmaengine_terminate_all().

How about adding that at here (I will wrap it up of course):
https://elixir.bootlin.com/linux/v4.19.5/source/drivers/mmc/host/sdhci.c#L2553

Is there somewhere else I'm missing?

Thanks,
Chunyan
Adrian Hunter Nov. 29, 2018, 10:39 a.m. | #6
On 29/11/18 11:44 AM, Chunyan Zhang wrote:
> On Thu, 29 Nov 2018 at 17:25, Adrian Hunter <adrian.hunter@intel.com> wrote:

>>

>> On 29/11/18 8:07 AM, Chunyan Zhang wrote:

>>> Some standard SD host controllers can support both external dma

>>> controllers as well as ADMA/SDMA in which the SD host controller

>>> acts as DMA master. TI's omap controller is the case as an example.

>>>

>>> Currently the generic SDHCI code supports ADMA/SDMA integrated in

>>> the host controller but does not have any support for external DMA

>>> controllers implemented using dmaengine, meaning that custom code is

>>> needed for any systems that use an external DMA controller with SDHCI.

>>>

>>> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

>>> ---

>>>  drivers/mmc/host/Kconfig |  14 ++++

>>>  drivers/mmc/host/sdhci.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++-

>>>  drivers/mmc/host/sdhci.h |   8 ++

>>>  3 files changed, 206 insertions(+), 1 deletion(-)

>>>

>>> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

>>> index 1b58739..4183f43 100644

>>> --- a/drivers/mmc/host/Kconfig

>>> +++ b/drivers/mmc/host/Kconfig

>>> @@ -969,6 +969,7 @@ config MMC_SDHCI_XENON

>>>  config MMC_SDHCI_OMAP

>>>       tristate "TI SDHCI Controller Support"

>>>       depends on MMC_SDHCI_PLTFM && OF

>>> +     select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE

>>>       help

>>>         This selects the Secure Digital Host Controller Interface (SDHCI)

>>>         support present in TI's DRA7 SOCs. The controller supports

>>> @@ -977,3 +978,16 @@ config MMC_SDHCI_OMAP

>>>         If you have a controller with this interface, say Y or M here.

>>>

>>>         If unsure, say N.

>>> +

>>> +config MMC_SDHCI_EXTERNAL_DMA

>>> +        bool "Support external DMA in standard SD host controller"

>>> +     depends on MMC_SDHCI

>>> +     depends on DMA_ENGINE

>>> +     help

>>> +       This is an option for using external DMA device via dmaengine

>>> +       framework.

>>> +

>>> +       If you have a controller which support using external DMA device

>>> +       for data transfer, can say Y.

>>> +

>>> +       If unsure, say N.

>>

>> So if you are going to select this, then you don't need the prompt or help

>> anymore i.e.

>>

>> config MMC_SDHCI_EXTERNAL_DMA

>>         bool

>>

>>

>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c

>>> index 99bdae5..ad7cc80 100644

>>> --- a/drivers/mmc/host/sdhci.c

>>> +++ b/drivers/mmc/host/sdhci.c

>>> @@ -14,6 +14,7 @@

>>>   */

>>>

>>>  #include <linux/delay.h>

>>> +#include <linux/dmaengine.h>

>>>  #include <linux/ktime.h>

>>>  #include <linux/highmem.h>

>>>  #include <linux/io.h>

>>> @@ -1309,6 +1310,162 @@ static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)

>>>               del_timer(&host->timer);

>>>  }

>>>

>>> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

>>> +static int sdhci_external_dma_init(struct sdhci_host *host)

>>> +{

>>> +     int ret = 0;

>>> +     struct mmc_host *mmc = host->mmc;

>>> +

>>> +     host->tx_chan = dma_request_chan(mmc->parent, "tx");

>>> +     if (IS_ERR(host->tx_chan)) {

>>> +             ret = PTR_ERR(host->tx_chan);

>>> +             if (ret != -EPROBE_DEFER)

>>> +                     pr_warn("Failed to request TX DMA channel.\n");

>>> +             host->tx_chan = NULL;

>>> +             return ret;

>>> +     }

>>> +

>>> +     host->rx_chan = dma_request_chan(mmc->parent, "rx");

>>> +     if (IS_ERR(host->rx_chan)) {

>>> +             if (host->tx_chan) {

>>> +                     dma_release_channel(host->tx_chan);

>>> +                     host->tx_chan = NULL;

>>> +             }

>>> +

>>> +             ret = PTR_ERR(host->rx_chan);

>>> +             if (ret != -EPROBE_DEFER)

>>> +                     pr_warn("Failed to request RX DMA channel.\n");

>>> +             host->rx_chan = NULL;

>>> +     }

>>> +

>>> +     return ret;

>>> +}

>>> +

>>> +static inline struct dma_chan *

>>> +sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)

>>> +{

>>> +     return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;

>>> +}

>>> +

>>> +static int sdhci_external_dma_setup(struct sdhci_host *host,

>>> +                                 struct mmc_command *cmd)

>>> +{

>>> +     int ret, i;

>>> +     struct dma_async_tx_descriptor *desc;

>>> +     struct mmc_data *data = cmd->data;

>>> +     struct dma_chan *chan;

>>> +     struct dma_slave_config cfg;

>>> +     dma_cookie_t cookie;

>>> +

>>> +     if (!host->mapbase)

>>> +             return -EINVAL;

>>> +

>>> +     if (!data)

>>> +             return 0;

>>

>> It would read better if the above 2 if-statements were the other way around i.e.

>>

>>         if (!data)

>>                 return 0;

>>

>>         if (!host->mapbase)

>>                 return -EINVAL;

>>

> 

> Ok.

> 

>>> +

>>> +     cfg.src_addr = host->mapbase + SDHCI_BUFFER;

>>> +     cfg.dst_addr = host->mapbase + SDHCI_BUFFER;

>>> +     cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

>>> +     cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

>>> +     cfg.src_maxburst = data->blksz / 4;

>>> +     cfg.dst_maxburst = data->blksz / 4;

>>> +

>>> +     /* Sanity check: all the SG entries must be aligned by block size. */

>>> +     for (i = 0; i < data->sg_len; i++) {

>>> +             if ((data->sg + i)->length % data->blksz)

>>> +                     return -EINVAL;

>>> +     }

>>> +

>>> +     chan = sdhci_external_dma_channel(host, data);

>>> +

>>> +     ret = dmaengine_slave_config(chan, &cfg);

>>> +     if (ret)

>>> +             return ret;

>>> +

>>> +     desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,

>>> +                                    mmc_get_dma_dir(data),

>>> +                                    DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

>>> +     if (!desc)

>>> +             return -EINVAL;

>>> +

>>> +     desc->callback = NULL;

>>> +     desc->callback_param = NULL;

>>> +

>>> +     cookie = dmaengine_submit(desc);

>>> +     if (cookie < 0)

>>> +             ret = cookie;

>>> +

>>> +     return ret;

>>> +}

>>> +

>>> +static void sdhci_external_dma_release(struct sdhci_host *host)

>>> +{

>>> +     if (host->tx_chan) {

>>> +             dma_release_channel(host->tx_chan);

>>> +             host->tx_chan = NULL;

>>> +     }

>>> +

>>> +     if (host->rx_chan) {

>>> +             dma_release_channel(host->rx_chan);

>>> +             host->rx_chan = NULL;

>>> +     }

>>> +

>>> +     sdhci_switch_external_dma(host, false);

>>> +}

>>> +

>>> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

>>> +                                         struct mmc_command *cmd)

>>> +{

>>> +     if (sdhci_external_dma_setup(host, cmd)) {

>>> +             sdhci_external_dma_release(host);

>>> +             pr_err("%s: Failed to setup external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",

>>> +                    mmc_hostname(host->mmc));

>>> +     } else {

>>> +             /* Prepare for using external dma */

>>> +             host->flags |= SDHCI_REQ_USE_DMA;

>>> +     }

>>> +

>>> +     sdhci_prepare_data(host, cmd);

>>> +}

>>> +

>>> +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

>>> +                                         struct mmc_command *cmd)

>>> +{

>>> +     struct dma_chan *chan;

>>> +

>>> +     if (cmd->opcode != MMC_SET_BLOCK_COUNT && cmd->data) {

>>

>> MMC_SET_BLOCK_COUNT doesn't have data so that part is not needed

> 

> Didn't get you here.

> This is for other packets except MMC_SET_BLOCK_COUNT.

> 


MMC_SET_BLOCK_COUNT is not a data transfer command, so cmd->data == NULL anyway.
Chunyan Zhang Nov. 29, 2018, 10:46 a.m. | #7
On Thu, 29 Nov 2018 at 18:41, Adrian Hunter <adrian.hunter@intel.com> wrote:
>

> On 29/11/18 11:44 AM, Chunyan Zhang wrote:

> > On Thu, 29 Nov 2018 at 17:25, Adrian Hunter <adrian.hunter@intel.com> wrote:

> >>

> >> On 29/11/18 8:07 AM, Chunyan Zhang wrote:

> >>> Some standard SD host controllers can support both external dma

> >>> controllers as well as ADMA/SDMA in which the SD host controller

> >>> acts as DMA master. TI's omap controller is the case as an example.

> >>>

> >>> Currently the generic SDHCI code supports ADMA/SDMA integrated in

> >>> the host controller but does not have any support for external DMA

> >>> controllers implemented using dmaengine, meaning that custom code is

> >>> needed for any systems that use an external DMA controller with SDHCI.

> >>>

> >>> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

> >>> ---

> >>>  drivers/mmc/host/Kconfig |  14 ++++

> >>>  drivers/mmc/host/sdhci.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++-

> >>>  drivers/mmc/host/sdhci.h |   8 ++

> >>>  3 files changed, 206 insertions(+), 1 deletion(-)

> >>>

> >>> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

> >>> index 1b58739..4183f43 100644

> >>> --- a/drivers/mmc/host/Kconfig

> >>> +++ b/drivers/mmc/host/Kconfig

> >>> @@ -969,6 +969,7 @@ config MMC_SDHCI_XENON

> >>>  config MMC_SDHCI_OMAP

> >>>       tristate "TI SDHCI Controller Support"

> >>>       depends on MMC_SDHCI_PLTFM && OF

> >>> +     select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE

> >>>       help

> >>>         This selects the Secure Digital Host Controller Interface (SDHCI)

> >>>         support present in TI's DRA7 SOCs. The controller supports

> >>> @@ -977,3 +978,16 @@ config MMC_SDHCI_OMAP

> >>>         If you have a controller with this interface, say Y or M here.

> >>>

> >>>         If unsure, say N.

> >>> +

> >>> +config MMC_SDHCI_EXTERNAL_DMA

> >>> +        bool "Support external DMA in standard SD host controller"

> >>> +     depends on MMC_SDHCI

> >>> +     depends on DMA_ENGINE

> >>> +     help

> >>> +       This is an option for using external DMA device via dmaengine

> >>> +       framework.

> >>> +

> >>> +       If you have a controller which support using external DMA device

> >>> +       for data transfer, can say Y.

> >>> +

> >>> +       If unsure, say N.

> >>

> >> So if you are going to select this, then you don't need the prompt or help

> >> anymore i.e.

> >>

> >> config MMC_SDHCI_EXTERNAL_DMA

> >>         bool

> >>

> >>

> >>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c

> >>> index 99bdae5..ad7cc80 100644

> >>> --- a/drivers/mmc/host/sdhci.c

> >>> +++ b/drivers/mmc/host/sdhci.c

> >>> @@ -14,6 +14,7 @@

> >>>   */

> >>>

> >>>  #include <linux/delay.h>

> >>> +#include <linux/dmaengine.h>

> >>>  #include <linux/ktime.h>

> >>>  #include <linux/highmem.h>

> >>>  #include <linux/io.h>

> >>> @@ -1309,6 +1310,162 @@ static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)

> >>>               del_timer(&host->timer);

> >>>  }

> >>>

> >>> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

> >>> +static int sdhci_external_dma_init(struct sdhci_host *host)

> >>> +{

> >>> +     int ret = 0;

> >>> +     struct mmc_host *mmc = host->mmc;

> >>> +

> >>> +     host->tx_chan = dma_request_chan(mmc->parent, "tx");

> >>> +     if (IS_ERR(host->tx_chan)) {

> >>> +             ret = PTR_ERR(host->tx_chan);

> >>> +             if (ret != -EPROBE_DEFER)

> >>> +                     pr_warn("Failed to request TX DMA channel.\n");

> >>> +             host->tx_chan = NULL;

> >>> +             return ret;

> >>> +     }

> >>> +

> >>> +     host->rx_chan = dma_request_chan(mmc->parent, "rx");

> >>> +     if (IS_ERR(host->rx_chan)) {

> >>> +             if (host->tx_chan) {

> >>> +                     dma_release_channel(host->tx_chan);

> >>> +                     host->tx_chan = NULL;

> >>> +             }

> >>> +

> >>> +             ret = PTR_ERR(host->rx_chan);

> >>> +             if (ret != -EPROBE_DEFER)

> >>> +                     pr_warn("Failed to request RX DMA channel.\n");

> >>> +             host->rx_chan = NULL;

> >>> +     }

> >>> +

> >>> +     return ret;

> >>> +}

> >>> +

> >>> +static inline struct dma_chan *

> >>> +sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)

> >>> +{

> >>> +     return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;

> >>> +}

> >>> +

> >>> +static int sdhci_external_dma_setup(struct sdhci_host *host,

> >>> +                                 struct mmc_command *cmd)

> >>> +{

> >>> +     int ret, i;

> >>> +     struct dma_async_tx_descriptor *desc;

> >>> +     struct mmc_data *data = cmd->data;

> >>> +     struct dma_chan *chan;

> >>> +     struct dma_slave_config cfg;

> >>> +     dma_cookie_t cookie;

> >>> +

> >>> +     if (!host->mapbase)

> >>> +             return -EINVAL;

> >>> +

> >>> +     if (!data)

> >>> +             return 0;

> >>

> >> It would read better if the above 2 if-statements were the other way around i.e.

> >>

> >>         if (!data)

> >>                 return 0;

> >>

> >>         if (!host->mapbase)

> >>                 return -EINVAL;

> >>

> >

> > Ok.

> >

> >>> +

> >>> +     cfg.src_addr = host->mapbase + SDHCI_BUFFER;

> >>> +     cfg.dst_addr = host->mapbase + SDHCI_BUFFER;

> >>> +     cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> >>> +     cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> >>> +     cfg.src_maxburst = data->blksz / 4;

> >>> +     cfg.dst_maxburst = data->blksz / 4;

> >>> +

> >>> +     /* Sanity check: all the SG entries must be aligned by block size. */

> >>> +     for (i = 0; i < data->sg_len; i++) {

> >>> +             if ((data->sg + i)->length % data->blksz)

> >>> +                     return -EINVAL;

> >>> +     }

> >>> +

> >>> +     chan = sdhci_external_dma_channel(host, data);

> >>> +

> >>> +     ret = dmaengine_slave_config(chan, &cfg);

> >>> +     if (ret)

> >>> +             return ret;

> >>> +

> >>> +     desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,

> >>> +                                    mmc_get_dma_dir(data),

> >>> +                                    DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

> >>> +     if (!desc)

> >>> +             return -EINVAL;

> >>> +

> >>> +     desc->callback = NULL;

> >>> +     desc->callback_param = NULL;

> >>> +

> >>> +     cookie = dmaengine_submit(desc);

> >>> +     if (cookie < 0)

> >>> +             ret = cookie;

> >>> +

> >>> +     return ret;

> >>> +}

> >>> +

> >>> +static void sdhci_external_dma_release(struct sdhci_host *host)

> >>> +{

> >>> +     if (host->tx_chan) {

> >>> +             dma_release_channel(host->tx_chan);

> >>> +             host->tx_chan = NULL;

> >>> +     }

> >>> +

> >>> +     if (host->rx_chan) {

> >>> +             dma_release_channel(host->rx_chan);

> >>> +             host->rx_chan = NULL;

> >>> +     }

> >>> +

> >>> +     sdhci_switch_external_dma(host, false);

> >>> +}

> >>> +

> >>> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> >>> +                                         struct mmc_command *cmd)

> >>> +{

> >>> +     if (sdhci_external_dma_setup(host, cmd)) {

> >>> +             sdhci_external_dma_release(host);

> >>> +             pr_err("%s: Failed to setup external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",

> >>> +                    mmc_hostname(host->mmc));

> >>> +     } else {

> >>> +             /* Prepare for using external dma */

> >>> +             host->flags |= SDHCI_REQ_USE_DMA;

> >>> +     }

> >>> +

> >>> +     sdhci_prepare_data(host, cmd);

> >>> +}

> >>> +

> >>> +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,

> >>> +                                         struct mmc_command *cmd)

> >>> +{

> >>> +     struct dma_chan *chan;

> >>> +

> >>> +     if (cmd->opcode != MMC_SET_BLOCK_COUNT && cmd->data) {

> >>

> >> MMC_SET_BLOCK_COUNT doesn't have data so that part is not needed

> >

> > Didn't get you here.

> > This is for other packets except MMC_SET_BLOCK_COUNT.

> >

>

> MMC_SET_BLOCK_COUNT is not a data transfer command, so cmd->data == NULL anyway.


Oh, got you.
"if (cmd->data)" is enough here :)

Thank you,
Chunyan
Adrian Hunter Nov. 29, 2018, 10:48 a.m. | #8
On 29/11/18 11:59 AM, Chunyan Zhang wrote:
> Hi Adrian,

> 

> On Thu, 29 Nov 2018 at 15:36, Adrian Hunter <adrian.hunter@intel.com> wrote:

>>

>> On 29/11/18 8:22 AM, Chunyan Zhang wrote:

>>> On Tue, 20 Nov 2018 at 21:41, Adrian Hunter <adrian.hunter@intel.com> wrote:

>>>>

>>>> On 12/11/18 9:26 AM, Chunyan Zhang wrote:

>>>>> Some standard SD host controllers can support both external dma

>>>>> controllers as well as ADMA/SDMA in which the SD host controller

>>>>> acts as DMA master. TI's omap controller is the case as an example.

>>>>>

>>>>> Currently the generic SDHCI code supports ADMA/SDMA integrated in

>>>>> the host controller but does not have any support for external DMA

>>>>> controllers implemented using dmaengine, meaning that custom code is

>>>>> needed for any systems that use an external DMA controller with SDHCI.

>>>>

>>>> I still think you probably need to reset the DMA if there are transfer

>>>> errors - perhaps you could comment on that.  Also there are some comments below.

>>>

>>> With regard to "transfer error", do you mean if

>>> sdhci_external_dma_setup() failed?

>>

>> No, I mean any error interrupt that can leave the DMA uncompleted.  For

>> SDHCI, resetting the data circuit cleans that up, but presumably something

>> is needed for external DMA?

> 

> Yes, it should need a dmaengine_terminate_all().

> 

> How about adding that at here (I will wrap it up of course):

> https://elixir.bootlin.com/linux/v4.19.5/source/drivers/mmc/host/sdhci.c#L2553


Yes except we really need to reverse
	if (host->flags & SDHCI_REQ_USE_DMA) {
	}
	if (sdhci_needs_reset(host, mrq)) {
	}
so that we do not unmap before killing the dma

Perhaps you could send that as a separate patch.

> Is there somewhere else I'm missing?


Testing ;-)
Shawn Lin Nov. 30, 2018, 1:15 a.m. | #9
On 2018/11/29 17:59, Chunyan Zhang wrote:
> Hi Adrian,

> 

> On Thu, 29 Nov 2018 at 15:36, Adrian Hunter <adrian.hunter@intel.com> wrote:

>>

>> On 29/11/18 8:22 AM, Chunyan Zhang wrote:

>>> On Tue, 20 Nov 2018 at 21:41, Adrian Hunter <adrian.hunter@intel.com> wrote:

>>>>

>>>> On 12/11/18 9:26 AM, Chunyan Zhang wrote:

>>>>> Some standard SD host controllers can support both external dma

>>>>> controllers as well as ADMA/SDMA in which the SD host controller

>>>>> acts as DMA master. TI's omap controller is the case as an example.

>>>>>

>>>>> Currently the generic SDHCI code supports ADMA/SDMA integrated in

>>>>> the host controller but does not have any support for external DMA

>>>>> controllers implemented using dmaengine, meaning that custom code is

>>>>> needed for any systems that use an external DMA controller with SDHCI.

>>>>

>>>> I still think you probably need to reset the DMA if there are transfer

>>>> errors - perhaps you could comment on that.  Also there are some comments below.

>>>

>>> With regard to "transfer error", do you mean if

>>> sdhci_external_dma_setup() failed?

>>

>> No, I mean any error interrupt that can leave the DMA uncompleted.  For

>> SDHCI, resetting the data circuit cleans that up, but presumably something

>> is needed for external DMA?

> 

> Yes, it should need a dmaengine_terminate_all().

> 


No, dmaengine_terminate_all is deprecated for quite a long time.
Please use dmaengine_terminate_{async, sync}() instead.

See Documentation/dmaengine/client.txt


> How about adding that at here (I will wrap it up of course):

> https://elixir.bootlin.com/linux/v4.19.5/source/drivers/mmc/host/sdhci.c#L2553

> 

> Is there somewhere else I'm missing?

> 

> Thanks,

> Chunyan

> 

>
Faiz Abbas Dec. 3, 2018, 9:03 a.m. | #10
Hi Chunyan,

On 29/11/18 2:53 PM, Adrian Hunter wrote:
> On 29/11/18 8:07 AM, Chunyan Zhang wrote:

>> Some standard SD host controllers can support both external dma

>> controllers as well as ADMA/SDMA in which the SD host controller

>> acts as DMA master. TI's omap controller is the case as an example.

>>

>> Currently the generic SDHCI code supports ADMA/SDMA integrated in

>> the host controller but does not have any support for external DMA

>> controllers implemented using dmaengine, meaning that custom code is

>> needed for any systems that use an external DMA controller with SDHCI.

>>

>> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

>> ---

>>  drivers/mmc/host/Kconfig |  14 ++++

>>  drivers/mmc/host/sdhci.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++-

>>  drivers/mmc/host/sdhci.h |   8 ++

>>  3 files changed, 206 insertions(+), 1 deletion(-)

>>

>> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

>> index 1b58739..4183f43 100644

>> --- a/drivers/mmc/host/Kconfig

>> +++ b/drivers/mmc/host/Kconfig

>> @@ -969,6 +969,7 @@ config MMC_SDHCI_XENON

>>  config MMC_SDHCI_OMAP

>>  	tristate "TI SDHCI Controller Support">>  	depends on MMC_SDHCI_PLTFM && OF

>> +	select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE



This should be in patch 2.

Thanks,
Faiz
Chunyan Zhang Dec. 3, 2018, 10:46 a.m. | #11
On Mon, 3 Dec 2018 at 17:01, Faiz Abbas <faiz_abbas@ti.com> wrote:
>

> Hi Chunyan,

>

> On 29/11/18 2:53 PM, Adrian Hunter wrote:

> > On 29/11/18 8:07 AM, Chunyan Zhang wrote:

> >> Some standard SD host controllers can support both external dma

> >> controllers as well as ADMA/SDMA in which the SD host controller

> >> acts as DMA master. TI's omap controller is the case as an example.

> >>

> >> Currently the generic SDHCI code supports ADMA/SDMA integrated in

> >> the host controller but does not have any support for external DMA

> >> controllers implemented using dmaengine, meaning that custom code is

> >> needed for any systems that use an external DMA controller with SDHCI.

> >>

> >> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

> >> ---

> >>  drivers/mmc/host/Kconfig |  14 ++++

> >>  drivers/mmc/host/sdhci.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++-

> >>  drivers/mmc/host/sdhci.h |   8 ++

> >>  3 files changed, 206 insertions(+), 1 deletion(-)

> >>

> >> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

> >> index 1b58739..4183f43 100644

> >> --- a/drivers/mmc/host/Kconfig

> >> +++ b/drivers/mmc/host/Kconfig

> >> @@ -969,6 +969,7 @@ config MMC_SDHCI_XENON

> >>  config MMC_SDHCI_OMAP

> >>      tristate "TI SDHCI Controller Support">>        depends on MMC_SDHCI_PLTFM && OF

> >> +    select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE

>

>

> This should be in patch 2.


Ok, will move to.

Thanks,
Chunyan

>

> Thanks,

> Faiz
Faiz Abbas Dec. 3, 2018, 12:15 p.m. | #12
Hi,

On 29/11/18 11:37 AM, Chunyan Zhang wrote:
> Some standard SD host controllers can support both external dma

> controllers as well as ADMA/SDMA in which the SD host controller

> acts as DMA master. TI's omap controller is the case as an example.

> 

> Currently the generic SDHCI code supports ADMA/SDMA integrated in

> the host controller but does not have any support for external DMA

> controllers implemented using dmaengine, meaning that custom code is

> needed for any systems that use an external DMA controller with SDHCI.

> 

> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>

> ---

>  drivers/mmc/host/Kconfig |  14 ++++

>  drivers/mmc/host/sdhci.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++-

>  drivers/mmc/host/sdhci.h |   8 ++

>  3 files changed, 206 insertions(+), 1 deletion(-)

> 

> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig

> index 1b58739..4183f43 100644

> --- a/drivers/mmc/host/Kconfig

> +++ b/drivers/mmc/host/Kconfig

> @@ -969,6 +969,7 @@ config MMC_SDHCI_XENON

>  config MMC_SDHCI_OMAP

>  	tristate "TI SDHCI Controller Support"

>  	depends on MMC_SDHCI_PLTFM && OF

> +	select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE

>  	help

>  	  This selects the Secure Digital Host Controller Interface (SDHCI)

>  	  support present in TI's DRA7 SOCs. The controller supports

> @@ -977,3 +978,16 @@ config MMC_SDHCI_OMAP

>  	  If you have a controller with this interface, say Y or M here.

>  

>  	  If unsure, say N.

> +

> +config MMC_SDHCI_EXTERNAL_DMA

> +        bool "Support external DMA in standard SD host controller"

> +	depends on MMC_SDHCI

> +	depends on DMA_ENGINE

> +	help

> +	  This is an option for using external DMA device via dmaengine

> +	  framework.

> +

> +	  If you have a controller which support using external DMA device

> +	  for data transfer, can say Y.

> +

> +	  If unsure, say N.

> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c

> index 99bdae5..ad7cc80 100644

> --- a/drivers/mmc/host/sdhci.c

> +++ b/drivers/mmc/host/sdhci.c

> @@ -14,6 +14,7 @@

>   */

>  

>  #include <linux/delay.h>

> +#include <linux/dmaengine.h>

>  #include <linux/ktime.h>

>  #include <linux/highmem.h>

>  #include <linux/io.h>

> @@ -1309,6 +1310,162 @@ static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)

>  		del_timer(&host->timer);

>  }

>  

> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)

> +static int sdhci_external_dma_init(struct sdhci_host *host)

> +{

> +	int ret = 0;

> +	struct mmc_host *mmc = host->mmc;

> +

> +	host->tx_chan = dma_request_chan(mmc->parent, "tx");

> +	if (IS_ERR(host->tx_chan)) {

> +		ret = PTR_ERR(host->tx_chan);

> +		if (ret != -EPROBE_DEFER)

> +			pr_warn("Failed to request TX DMA channel.\n");

> +		host->tx_chan = NULL;

> +		return ret;

> +	}

> +

> +	host->rx_chan = dma_request_chan(mmc->parent, "rx");

> +	if (IS_ERR(host->rx_chan)) {

> +		if (host->tx_chan) {

> +			dma_release_channel(host->tx_chan);

> +			host->tx_chan = NULL;

> +		}

> +

> +		ret = PTR_ERR(host->rx_chan);

> +		if (ret != -EPROBE_DEFER)

> +			pr_warn("Failed to request RX DMA channel.\n");

> +		host->rx_chan = NULL;

> +	}

> +

> +	return ret;

> +}

> +

> +static inline struct dma_chan *

> +sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)

> +{

> +	return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;

> +}

> +

> +static int sdhci_external_dma_setup(struct sdhci_host *host,

> +				    struct mmc_command *cmd)

> +{

> +	int ret, i;

> +	struct dma_async_tx_descriptor *desc;

> +	struct mmc_data *data = cmd->data;

> +	struct dma_chan *chan;

> +	struct dma_slave_config cfg;

> +	dma_cookie_t cookie;

> +

> +	if (!host->mapbase)

> +		return -EINVAL;

> +

> +	if (!data)

> +		return 0;

> +

> +	cfg.src_addr = host->mapbase + SDHCI_BUFFER;

> +	cfg.dst_addr = host->mapbase + SDHCI_BUFFER;

> +	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> +	cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

> +	cfg.src_maxburst = data->blksz / 4;

> +	cfg.dst_maxburst = data->blksz / 4;

> +

> +	/* Sanity check: all the SG entries must be aligned by block size. */

> +	for (i = 0; i < data->sg_len; i++) {

> +		if ((data->sg + i)->length % data->blksz)

> +			return -EINVAL;

> +	}

> +

> +	chan = sdhci_external_dma_channel(host, data);

> +

> +	ret = dmaengine_slave_config(chan, &cfg);

> +	if (ret)

> +		return ret;

> +

> +	desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,

> +				       mmc_get_dma_dir(data),

> +				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

> +	if (!desc)

> +		return -EINVAL;

> +

> +	desc->callback = NULL;

> +	desc->callback_param = NULL;

> +

> +	cookie = dmaengine_submit(desc);

> +	if (cookie < 0)

> +		ret = cookie;

> +

> +	return ret;

> +}

> +

> +static void sdhci_external_dma_release(struct sdhci_host *host)

> +{

> +	if (host->tx_chan) {

> +		dma_release_channel(host->tx_chan);

> +		host->tx_chan = NULL;

> +	}

> +

> +	if (host->rx_chan) {

> +		dma_release_channel(host->rx_chan);

> +		host->rx_chan = NULL;

> +	}

> +

> +	sdhci_switch_external_dma(host, false);

> +}

> +

> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> +					    struct mmc_command *cmd)

> +{


Please add a condition for data == NULL here. This was already pointed
out by Adrian in v2.

My test with an am335x-evm failed with these patches. Looks like the
very first SDIO commands failing.

https://pastebin.ubuntu.com/p/Y2RDjSKpgd/

Currently am335x-evm is using omap_hsmmc driver. I added the following
patch to make it work with sdhci_omap.

https://pastebin.ubuntu.com/p/VTGrCbJxY3/

Will look deeper into this. Please ping if you need any more information.

Thanks,
Faiz
Faiz Abbas Dec. 3, 2018, 1:58 p.m. | #13
Hi,

On 03/12/18 5:45 PM, Faiz Abbas wrote:
> Hi,

> 

>> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

>> +					    struct mmc_command *cmd)

>> +{

> 

> Please add a condition for data == NULL here. This was already pointed

> out by Adrian in v2.

> 

> My test with an am335x-evm failed with these patches. Looks like the

> very first SDIO commands failing.

> 

> https://pastebin.ubuntu.com/p/Y2RDjSKpgd/

> 

> Currently am335x-evm is using omap_hsmmc driver. I added the following

> patch to make it work with sdhci_omap.

> 

> https://pastebin.ubuntu.com/p/VTGrCbJxY3/

> 

> Will look deeper into this. Please ping if you need any more information.

> 


So I disabled DMA in the driver altogether and still got the same
messages on am335x-evm in PIO mode. Looks like something more is
required for it to be supported.

I instead shifted to a dra71-evm which supports both ADMA and external
DMA. Here is the log:

https://pastebin.ubuntu.com/p/mcJmgcjQsp/

The interface fundamentally works but it complains with the following error:

[3.111693] Failed to request TX DMA channel.


Thanks,
Faiz
Chunyan Zhang Dec. 4, 2018, 3:11 a.m. | #14
Hi Faiz,

On Mon, 3 Dec 2018 at 21:55, Faiz Abbas <faiz_abbas@ti.com> wrote:
>

> Hi,

>

> On 03/12/18 5:45 PM, Faiz Abbas wrote:

> > Hi,

> >

> >> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,

> >> +                                        struct mmc_command *cmd)

> >> +{

> >

> > Please add a condition for data == NULL here. This was already pointed

> > out by Adrian in v2.


The check for data is added in sdhci_external_dma_setup() .

> >

> > My test with an am335x-evm failed with these patches. Looks like the

> > very first SDIO commands failing.


I guess you didn't add 'dmas' in device tree, like patch 3 shows.

> >

> > https://pastebin.ubuntu.com/p/Y2RDjSKpgd/

> >

> > Currently am335x-evm is using omap_hsmmc driver. I added the following

> > patch to make it work with sdhci_omap.

> >

> > https://pastebin.ubuntu.com/p/VTGrCbJxY3/

> >

> > Will look deeper into this. Please ping if you need any more information.

> >

>

> So I disabled DMA in the driver altogether and still got the same

> messages on am335x-evm in PIO mode. Looks like something more is

> required for it to be supported.

>

> I instead shifted to a dra71-evm which supports both ADMA and external

> DMA. Here is the log:

>

> https://pastebin.ubuntu.com/p/mcJmgcjQsp/

>

> The interface fundamentally works but it complains with the following error:

>


Yes, it switched back to ADMA/PIO since sdhci couldn't find 'dmas'
property in devicetree.

> [3.111693] Failed to request TX DMA channel.


Ok, I will add a check in sdhci-omap.c before switching to external
dma, that should be able to avoid this error logs.

Thanks for the review and test!

Chunyan

Patch

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 1b58739..7bf3eff 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -977,3 +977,16 @@  config MMC_SDHCI_OMAP
 	  If you have a controller with this interface, say Y or M here.
 
 	  If unsure, say N.
+
+config MMC_SDHCI_EXTERNAL_DMA
+        bool "Support external DMA in standard SD host controller"
+	depends on MMC_SDHCI
+	depends on DMA_ENGINE
+	help
+	  This is an option for using external DMA device via dmaengine
+	  framework.
+
+	  If you have a controller which support using external DMA device
+	  for data transfer, can say Y.
+
+	  If unsure, say N.
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 99bdae5..853cc98 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -14,6 +14,7 @@ 
  */
 
 #include <linux/delay.h>
+#include <linux/dmaengine.h>
 #include <linux/ktime.h>
 #include <linux/highmem.h>
 #include <linux/io.h>
@@ -1309,6 +1310,158 @@  static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)
 		del_timer(&host->timer);
 }
 
+#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)
+static int sdhci_external_dma_init(struct sdhci_host *host)
+{
+	int ret = 0;
+	struct mmc_host *mmc = host->mmc;
+
+	host->tx_chan = dma_request_chan(mmc->parent, "tx");
+	if (IS_ERR(host->tx_chan)) {
+		ret = PTR_ERR(host->tx_chan);
+		if (ret != -EPROBE_DEFER)
+			pr_warn("Failed to request TX DMA channel.\n");
+		host->tx_chan = NULL;
+		return ret;
+	}
+
+	host->rx_chan = dma_request_chan(mmc->parent, "rx");
+	if (IS_ERR(host->rx_chan)) {
+		if (host->tx_chan) {
+			dma_release_channel(host->tx_chan);
+			host->tx_chan = NULL;
+		}
+
+		ret = PTR_ERR(host->rx_chan);
+		if (ret != -EPROBE_DEFER)
+			pr_warn("Failed to request RX DMA channel.\n");
+		host->rx_chan = NULL;
+	}
+
+	return ret;
+}
+
+static inline struct dma_chan *
+sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)
+{
+	return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;
+}
+
+static int sdhci_external_dma_setup(struct sdhci_host *host,
+				    struct mmc_command *cmd)
+{
+	int ret = 0, i;
+	struct dma_async_tx_descriptor *desc;
+	struct mmc_data *data = cmd->data;
+	struct dma_chan *chan;
+	struct dma_slave_config cfg;
+	dma_cookie_t cookie;
+
+	if (!host->mapbase)
+		return -EINVAL;
+
+	cfg.src_addr = host->mapbase + SDHCI_BUFFER;
+	cfg.dst_addr = host->mapbase + SDHCI_BUFFER;
+	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	cfg.src_maxburst = data->blksz / 4;
+	cfg.dst_maxburst = data->blksz / 4;
+
+	/* Sanity check: all the SG entries must be aligned by block size. */
+	for (i = 0; i < data->sg_len; i++) {
+		if ((data->sg + i)->length % data->blksz)
+			return -EINVAL;
+	}
+
+	chan = sdhci_external_dma_channel(host, data);
+
+	ret = dmaengine_slave_config(chan, &cfg);
+	if (ret)
+		return ret;
+
+	desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,
+				       mmc_get_dma_dir(data),
+				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!desc)
+		return -EINVAL;
+
+	desc->callback = NULL;
+	desc->callback_param = NULL;
+
+	cookie = dmaengine_submit(desc);
+	if (cookie < 0)
+		ret = cookie;
+
+	return ret;
+}
+
+static void sdhci_external_dma_release(struct sdhci_host *host)
+{
+	if (host->tx_chan) {
+		dma_release_channel(host->tx_chan);
+		host->tx_chan = NULL;
+	}
+
+	if (host->rx_chan) {
+		dma_release_channel(host->rx_chan);
+		host->rx_chan = NULL;
+	}
+
+	sdhci_switch_external_dma(host, false);
+}
+
+static void sdhci_external_dma_prepare_data(struct sdhci_host *host,
+					    struct mmc_command *cmd)
+{
+	if (sdhci_external_dma_setup(host, cmd)) {
+		sdhci_external_dma_release(host);
+		pr_err("%s: Failed to setup external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",
+		       mmc_hostname(host->mmc));
+	} else {
+		/* Prepare for using external dma */
+		host->flags |= SDHCI_REQ_USE_DMA;
+	}
+
+	sdhci_prepare_data(host, cmd);
+}
+
+static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
+					    struct mmc_command *cmd)
+{
+	struct dma_chan *chan = sdhci_external_dma_channel(host, cmd->data);
+
+	if (cmd->opcode != MMC_SET_BLOCK_COUNT) {
+		sdhci_set_timeout(host, cmd);
+		dma_async_issue_pending(chan);
+	}
+}
+#else
+static int sdhci_external_dma_init(struct sdhci_host *host)
+{
+	return 0;
+}
+
+static void sdhci_external_dma_release(struct sdhci_host *host)
+{}
+
+static void sdhci_external_dma_prepare_data(struct sdhci_host *host,
+					    struct mmc_command *cmd)
+{
+	/* If SDHCI_EXTDMA not supported, PIO will be used */
+	sdhci_prepare_data(host, cmd);
+}
+
+static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
+					    struct mmc_command *cmd)
+{}
+#endif
+
+void sdhci_switch_external_dma(struct sdhci_host *host, bool en)
+{
+	host->use_external_dma = en;
+}
+EXPORT_SYMBOL_GPL(sdhci_switch_external_dma);
+
 void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
 {
 	int flags;
@@ -1355,7 +1508,10 @@  void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
 		host->data_cmd = cmd;
 	}
 
-	sdhci_prepare_data(host, cmd);
+	if (host->use_external_dma)
+		sdhci_external_dma_prepare_data(host, cmd);
+	else
+		sdhci_prepare_data(host, cmd);
 
 	sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);
 
@@ -1397,6 +1553,9 @@  void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
 		timeout += 10 * HZ;
 	sdhci_mod_timer(host, cmd->mrq, timeout);
 
+	if (host->use_external_dma)
+		sdhci_external_dma_pre_transfer(host, cmd);
+
 	sdhci_writew(host, SDHCI_MAKE_CMD(cmd->opcode, flags), SDHCI_COMMAND);
 }
 EXPORT_SYMBOL_GPL(sdhci_send_command);
@@ -4133,6 +4292,19 @@  int sdhci_setup_host(struct sdhci_host *host)
 			return ret;
 	}
 
+	if (host->use_external_dma) {
+		ret = sdhci_external_dma_init(host);
+		if (ret == -EPROBE_DEFER)
+			goto unreg;
+
+		/*
+		 * Fall back to use the DMA/PIO integrated in standard SDHCI
+		 * instead of external DMA devices.
+		 */
+		if (ret)
+			sdhci_switch_external_dma(host, false);
+	}
+
 	return 0;
 
 unreg:
@@ -4161,6 +4333,10 @@  void sdhci_cleanup_host(struct sdhci_host *host)
 		dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz +
 				  host->adma_table_sz, host->align_buffer,
 				  host->align_addr);
+
+	if (host->use_external_dma)
+		sdhci_external_dma_release(host);
+
 	host->adma_table = NULL;
 	host->align_buffer = NULL;
 }
@@ -4295,6 +4471,9 @@  void sdhci_remove_host(struct sdhci_host *host, int dead)
 				  host->adma_table_sz, host->align_buffer,
 				  host->align_addr);
 
+	if (host->use_external_dma)
+		sdhci_external_dma_release(host);
+
 	host->adma_table = NULL;
 	host->align_buffer = NULL;
 }
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index b001cf4..8e50a97 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -475,6 +475,7 @@  struct sdhci_host {
 
 	int irq;		/* Device IRQ */
 	void __iomem *ioaddr;	/* Mapped address */
+	phys_addr_t mapbase;	/* physical address base */
 	char *bounce_buffer;	/* For packing SDMA reads/writes */
 	dma_addr_t bounce_addr;
 	unsigned int bounce_buffer_size;
@@ -524,6 +525,7 @@  struct sdhci_host {
 	bool pending_reset;	/* Cmd/data reset is pending */
 	bool irq_wake_enabled;	/* IRQ wakeup is enabled */
 	bool v4_mode;		/* Host Version 4 Enable */
+	bool use_external_dma;
 
 	struct mmc_request *mrqs_done[SDHCI_MAX_MRQS];	/* Requests done */
 	struct mmc_command *cmd;	/* Current command */
@@ -552,6 +554,11 @@  struct sdhci_host {
 	struct timer_list timer;	/* Timer for timeouts */
 	struct timer_list data_timer;	/* Timer for data timeouts */
 
+#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)
+	struct dma_chan	*rx_chan;
+	struct dma_chan	*tx_chan;
+#endif
+
 	u32 caps;		/* CAPABILITY_0 */
 	u32 caps1;		/* CAPABILITY_1 */
 	bool read_caps;		/* Capability flags have been read */
@@ -785,5 +792,6 @@  void sdhci_start_tuning(struct sdhci_host *host);
 void sdhci_end_tuning(struct sdhci_host *host);
 void sdhci_reset_tuning(struct sdhci_host *host);
 void sdhci_send_tuning(struct sdhci_host *host, u32 opcode);
+void sdhci_switch_external_dma(struct sdhci_host *host, bool en);
 
 #endif /* __SDHCI_HW_H */