mmc: omap_hsmmc: don't print uninitialized variables

Message ID 1453737031-1959584-1-git-send-email-arnd@arndb.de
State New
Headers show

Commit Message

Arnd Bergmann Jan. 25, 2016, 3:50 p.m.
When DT based probing is used but the DMA request fails, the
driver will print uninitialized stack data from the rx_req
and tx_req variables, as indicated by this warning:

drivers/mmc/host/omap_hsmmc.c: In function 'omap_hsmmc_probe':
drivers/mmc/host/omap_hsmmc.c:2162:3: warning: 'rx_req' may be used uninitialized in this function [-Wmaybe-uninitialized]
   dev_err(mmc_dev(host->mmc), "unable to obtain RX DMA engine channel %u\n", rx_req);

This restructures the function to separate the simple DT probe
from the more complex platform data code path, and only
prints the information that is actually available and
needed in case of an error, which makes it nicer to read
and avoids the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/mmc/host/omap_hsmmc.c | 48 +++++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 25 deletions(-)

-- 
2.7.0

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Comments

Peter Ujfalusi Jan. 26, 2016, 2:52 p.m. | #1
On 01/25/2016 05:50 PM, Arnd Bergmann wrote:
> When DT based probing is used but the DMA request fails, the

> driver will print uninitialized stack data from the rx_req

> and tx_req variables, as indicated by this warning:

> 

> drivers/mmc/host/omap_hsmmc.c: In function 'omap_hsmmc_probe':

> drivers/mmc/host/omap_hsmmc.c:2162:3: warning: 'rx_req' may be used uninitialized in this function [-Wmaybe-uninitialized]

>    dev_err(mmc_dev(host->mmc), "unable to obtain RX DMA engine channel %u\n", rx_req);

> 

> This restructures the function to separate the simple DT probe

> from the more complex platform data code path, and only

> prints the information that is actually available and

> needed in case of an error, which makes it nicer to read

> and avoids the warning.

> 

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

>  drivers/mmc/host/omap_hsmmc.c | 48 +++++++++++++++++++++----------------------

>  1 file changed, 23 insertions(+), 25 deletions(-)

> 

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

> index b6639ea0bf18..e06b1881b6a1 100644

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

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

> @@ -2002,8 +2002,6 @@ static int omap_hsmmc_probe(struct platform_device *pdev)

>  	struct resource *res;

>  	int ret, irq;

>  	const struct of_device_id *match;

> -	dma_cap_mask_t mask;

> -	unsigned tx_req, rx_req;

>  	const struct omap_mmc_of_data *data;

>  	void __iomem *base;

>  

> @@ -2133,7 +2131,17 @@ static int omap_hsmmc_probe(struct platform_device *pdev)

>  

>  	omap_hsmmc_conf_bus_power(host);

>  

> -	if (!pdev->dev.of_node) {

> +	host->tx_chan = dma_request_slave_channel(&pdev->dev, "tx");

> +	host->rx_chan = dma_request_slave_channel(&pdev->dev, "rx");

> +	if (!host->tx_chan || !host->rx_chan) {


While it is really unlikely that we are failing to get only one of the
channels... It means anyway that the omap_hsmmc is not usable, but we will
still try to get via legacy mode and there is a chance that we might get some
channel.

Too bad that I can not send the conversion to dma_request_chan() yet due to
missing things in arch...

It might be simpler to just remove the printout of the rx/tx_req from the
dev_err() when reporting failed channel requests...

> +		dma_cap_mask_t mask;

> +		unsigned tx_req, rx_req;

> +

> +		dev_err(mmc_dev(host->mmc), "falling back to manual DMA configuration\n");

> +

> +		dma_cap_zero(mask);

> +		dma_cap_set(DMA_SLAVE, mask);

> +

>  		res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "tx");

>  		if (!res) {

>  			dev_err(mmc_dev(host->mmc), "cannot get DMA TX channel\n");

> @@ -2141,6 +2149,12 @@ static int omap_hsmmc_probe(struct platform_device *pdev)

>  			goto err_irq;

>  		}

>  		tx_req = res->start;

> +		host->tx_chan = dma_request_channel(mask, omap_dma_filter_fn, &tx_req);

> +		if (!host->rx_chan) {

> +			dev_err(mmc_dev(host->mmc), "unable to obtain TX DMA engine channel %u\n", tx_req);

> +			ret = -ENXIO;

> +			goto err_irq;

> +		}

>  

>  		res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "rx");

>  		if (!res) {

> @@ -2149,29 +2163,13 @@ static int omap_hsmmc_probe(struct platform_device *pdev)

>  			goto err_irq;

>  		}

>  		rx_req = res->start;

> -	}

> -

> -	dma_cap_zero(mask);

> -	dma_cap_set(DMA_SLAVE, mask);

> -

> -	host->rx_chan =

> -		dma_request_slave_channel_compat(mask, omap_dma_filter_fn,

> -						 &rx_req, &pdev->dev, "rx");

> +		host->tx_chan = dma_request_channel(mask, omap_dma_filter_fn, &rx_req);

>  

> -	if (!host->rx_chan) {

> -		dev_err(mmc_dev(host->mmc), "unable to obtain RX DMA engine channel %u\n", rx_req);

> -		ret = -ENXIO;

> -		goto err_irq;

> -	}

> -

> -	host->tx_chan =

> -		dma_request_slave_channel_compat(mask, omap_dma_filter_fn,

> -						 &tx_req, &pdev->dev, "tx");

> -

> -	if (!host->tx_chan) {

> -		dev_err(mmc_dev(host->mmc), "unable to obtain TX DMA engine channel %u\n", tx_req);

> -		ret = -ENXIO;

> -		goto err_irq;

> +		if (!host->tx_chan) {

> +			dev_err(mmc_dev(host->mmc), "unable to obtain RX DMA engine channel %u\n", rx_req);

> +			ret = -ENXIO;

> +			goto err_irq;

> +		}

>  	}

>  

>  	/* Request IRQ for MMC operations */

> 



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Arnd Bergmann Jan. 26, 2016, 3:18 p.m. | #2
On Tuesday 26 January 2016 16:52:40 Peter Ujfalusi wrote:
> > @@ -2133,7 +2131,17 @@ static int omap_hsmmc_probe(struct platform_device *pdev)

> >  

> >       omap_hsmmc_conf_bus_power(host);

> >  

> > -     if (!pdev->dev.of_node) {

> > +     host->tx_chan = dma_request_slave_channel(&pdev->dev, "tx");

> > +     host->rx_chan = dma_request_slave_channel(&pdev->dev, "rx");

> > +     if (!host->tx_chan || !host->rx_chan) {

> 

> While it is really unlikely that we are failing to get only one of the

> channels... It means anyway that the omap_hsmmc is not usable, but we will

> still try to get via legacy mode and there is a chance that we might get some

> channel.

> 

> Too bad that I can not send the conversion to dma_request_chan() yet due to

> missing things in arch...

> 

> It might be simpler to just remove the printout of the rx/tx_req from the

> dev_err() when reporting failed channel requests...


Fine with me too, I'll send that patch as well and let Ulf pick.

	Arnd
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Patch

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index b6639ea0bf18..e06b1881b6a1 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -2002,8 +2002,6 @@  static int omap_hsmmc_probe(struct platform_device *pdev)
 	struct resource *res;
 	int ret, irq;
 	const struct of_device_id *match;
-	dma_cap_mask_t mask;
-	unsigned tx_req, rx_req;
 	const struct omap_mmc_of_data *data;
 	void __iomem *base;
 
@@ -2133,7 +2131,17 @@  static int omap_hsmmc_probe(struct platform_device *pdev)
 
 	omap_hsmmc_conf_bus_power(host);
 
-	if (!pdev->dev.of_node) {
+	host->tx_chan = dma_request_slave_channel(&pdev->dev, "tx");
+	host->rx_chan = dma_request_slave_channel(&pdev->dev, "rx");
+	if (!host->tx_chan || !host->rx_chan) {
+		dma_cap_mask_t mask;
+		unsigned tx_req, rx_req;
+
+		dev_err(mmc_dev(host->mmc), "falling back to manual DMA configuration\n");
+
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+
 		res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "tx");
 		if (!res) {
 			dev_err(mmc_dev(host->mmc), "cannot get DMA TX channel\n");
@@ -2141,6 +2149,12 @@  static int omap_hsmmc_probe(struct platform_device *pdev)
 			goto err_irq;
 		}
 		tx_req = res->start;
+		host->tx_chan = dma_request_channel(mask, omap_dma_filter_fn, &tx_req);
+		if (!host->rx_chan) {
+			dev_err(mmc_dev(host->mmc), "unable to obtain TX DMA engine channel %u\n", tx_req);
+			ret = -ENXIO;
+			goto err_irq;
+		}
 
 		res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "rx");
 		if (!res) {
@@ -2149,29 +2163,13 @@  static int omap_hsmmc_probe(struct platform_device *pdev)
 			goto err_irq;
 		}
 		rx_req = res->start;
-	}
-
-	dma_cap_zero(mask);
-	dma_cap_set(DMA_SLAVE, mask);
-
-	host->rx_chan =
-		dma_request_slave_channel_compat(mask, omap_dma_filter_fn,
-						 &rx_req, &pdev->dev, "rx");
+		host->tx_chan = dma_request_channel(mask, omap_dma_filter_fn, &rx_req);
 
-	if (!host->rx_chan) {
-		dev_err(mmc_dev(host->mmc), "unable to obtain RX DMA engine channel %u\n", rx_req);
-		ret = -ENXIO;
-		goto err_irq;
-	}
-
-	host->tx_chan =
-		dma_request_slave_channel_compat(mask, omap_dma_filter_fn,
-						 &tx_req, &pdev->dev, "tx");
-
-	if (!host->tx_chan) {
-		dev_err(mmc_dev(host->mmc), "unable to obtain TX DMA engine channel %u\n", tx_req);
-		ret = -ENXIO;
-		goto err_irq;
+		if (!host->tx_chan) {
+			dev_err(mmc_dev(host->mmc), "unable to obtain RX DMA engine channel %u\n", rx_req);
+			ret = -ENXIO;
+			goto err_irq;
+		}
 	}
 
 	/* Request IRQ for MMC operations */