[v6] mmc: sdhci-of-dwcmshc: Add runtime PM operations

This commit implements the runtime PM operations to disable eMMC
card clock when idle.

Reviewed-by: David Thompson <davthompson@nvidia.com>
Signed-off-by: Liming Sun <limings@nvidia.com>
---
v5->v6:
    - Address Adrian's more comments and add coordination between
      runtime PM and system PM;
v4->v5:
    - Address Adrian's comment to move the pm_enable to the end to
      avoid race;
v3->v4:
    - Fix compiling reported by 'kernel test robot';
v2->v3:
    - Revise the commit message;
v1->v2:
    Updates for comments from Ulf:
    - Make the runtime PM logic generic for sdhci-of-dwcmshc;
v1: Initial version.
---
 drivers/mmc/host/sdhci-of-dwcmshc.c | 72 ++++++++++++++++++++++++++++-
 1 file changed, 70 insertions(+), 2 deletions(-)

On Sat, 5 Aug 2023 at 01:30, Liming Sun <limings@nvidia.com> wrote:
>
> This commit implements the runtime PM operations to disable eMMC
> card clock when idle.
>
> Reviewed-by: David Thompson <davthompson@nvidia.com>
> Signed-off-by: Liming Sun <limings@nvidia.com>
> ---
> v5->v6:
>     - Address Adrian's more comments and add coordination between
>       runtime PM and system PM;
> v4->v5:
>     - Address Adrian's comment to move the pm_enable to the end to
>       avoid race;
> v3->v4:
>     - Fix compiling reported by 'kernel test robot';
> v2->v3:
>     - Revise the commit message;
> v1->v2:
>     Updates for comments from Ulf:
>     - Make the runtime PM logic generic for sdhci-of-dwcmshc;
> v1: Initial version.
> ---
>  drivers/mmc/host/sdhci-of-dwcmshc.c | 72 ++++++++++++++++++++++++++++-
>  1 file changed, 70 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index e68cd87998c8..aaf66358f626 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -15,6 +15,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/reset.h>
>  #include <linux/sizes.h>
>
> @@ -548,9 +549,13 @@ static int dwcmshc_probe(struct platform_device *pdev)
>
>         host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
>
> +       pm_runtime_get_noresume(dev);
> +       pm_runtime_set_active(dev);
> +       pm_runtime_enable(dev);
> +
>         err = sdhci_setup_host(host);
>         if (err)
> -               goto err_clk;
> +               goto err_rpm;
>
>         if (rk_priv)
>                 dwcmshc_rk35xx_postinit(host, priv);
> @@ -559,10 +564,15 @@ static int dwcmshc_probe(struct platform_device *pdev)
>         if (err)
>                 goto err_setup_host;
>
> +       pm_runtime_put_sync(dev);
> +

The async pm_runtime_put() is probably sufficient - and it would allow
the probe to complete a bit "sooner".

>         return 0;
>
>  err_setup_host:
>         sdhci_cleanup_host(host);
> +err_rpm:
> +       pm_runtime_disable(dev);
> +       pm_runtime_put_noidle(dev);
>  err_clk:
>         clk_disable_unprepare(pltfm_host->clk);
>         clk_disable_unprepare(priv->bus_clk);
> @@ -606,6 +616,12 @@ static int dwcmshc_suspend(struct device *dev)
>         if (ret)
>                 return ret;
>
> +       ret = pm_runtime_force_suspend(dev);

Can dwcmshc_suspend() be called for a device that may be attached to
the ACPI PM domain?

> +       if (ret) {
> +               sdhci_resume_host(host);
> +               return ret;
> +       }
> +
>         clk_disable_unprepare(pltfm_host->clk);
>         if (!IS_ERR(priv->bus_clk))
>                 clk_disable_unprepare(priv->bus_clk);
> @@ -625,6 +641,10 @@ static int dwcmshc_resume(struct device *dev)
>         struct rk35xx_priv *rk_priv = priv->priv;
>         int ret;
>
> +       ret = pm_runtime_force_resume(dev);
> +       if (ret)
> +               return ret;
> +
>         ret = clk_prepare_enable(pltfm_host->clk);
>         if (ret)
>                 return ret;
> @@ -646,7 +666,55 @@ static int dwcmshc_resume(struct device *dev)
>  }
>  #endif
>
> -static SIMPLE_DEV_PM_OPS(dwcmshc_pmops, dwcmshc_suspend, dwcmshc_resume);
> +#ifdef CONFIG_PM
> +
> +static void dwcmshc_enable_card_clk(struct sdhci_host *host)
> +{
> +       u16 ctrl;
> +
> +       ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +       if ((ctrl & SDHCI_CLOCK_INT_EN) && !(ctrl & SDHCI_CLOCK_CARD_EN)) {
> +               ctrl |= SDHCI_CLOCK_CARD_EN;
> +               sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
> +       }
> +}
> +
> +static void dwcmshc_disable_card_clk(struct sdhci_host *host)
> +{
> +       u16 ctrl;
> +
> +       ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +       if (ctrl & SDHCI_CLOCK_CARD_EN) {
> +               ctrl &= ~SDHCI_CLOCK_CARD_EN;
> +               sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
> +       }
> +}
> +
> +static int dwcmshc_runtime_suspend(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +
> +       dwcmshc_disable_card_clk(host);
> +
> +       return 0;
> +}
> +
> +static int dwcmshc_runtime_resume(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +
> +       dwcmshc_enable_card_clk(host);
> +
> +       return 0;
> +}
> +
> +#endif
> +
> +static const struct dev_pm_ops dwcmshc_pmops = {
> +       SET_SYSTEM_SLEEP_PM_OPS(dwcmshc_suspend, dwcmshc_resume)
> +       SET_RUNTIME_PM_OPS(dwcmshc_runtime_suspend,
> +                          dwcmshc_runtime_resume, NULL)
> +};
>
>  static struct platform_driver sdhci_dwcmshc_driver = {
>         .driver = {
> --

Kind regards
Uffe

> -----Original Message-----
> From: Ulf Hansson <ulf.hansson@linaro.org>
> Sent: Tuesday, August 8, 2023 5:40 AM
> To: Liming Sun <limings@nvidia.com>
> Cc: Adrian Hunter <adrian.hunter@intel.com>; David Thompson
> <davthompson@nvidia.com>; Shawn Lin <shawn.lin@rock-chips.com>; linux-
> mmc@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v6] mmc: sdhci-of-dwcmshc: Add runtime PM operations
> 
> On Sat, 5 Aug 2023 at 01:30, Liming Sun <limings@nvidia.com> wrote:
> >
> > This commit implements the runtime PM operations to disable eMMC
> > card clock when idle.
> >
> > Reviewed-by: David Thompson <davthompson@nvidia.com>
> > Signed-off-by: Liming Sun <limings@nvidia.com>
> > ---
> > v5->v6:
> >     - Address Adrian's more comments and add coordination between
> >       runtime PM and system PM;
> > v4->v5:
> >     - Address Adrian's comment to move the pm_enable to the end to
> >       avoid race;
> > v3->v4:
> >     - Fix compiling reported by 'kernel test robot';
> > v2->v3:
> >     - Revise the commit message;
> > v1->v2:
> >     Updates for comments from Ulf:
> >     - Make the runtime PM logic generic for sdhci-of-dwcmshc;
> > v1: Initial version.
> > ---
> >  drivers/mmc/host/sdhci-of-dwcmshc.c | 72
> ++++++++++++++++++++++++++++-
> >  1 file changed, 70 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-
> of-dwcmshc.c
> > index e68cd87998c8..aaf66358f626 100644
> > --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> > +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> > @@ -15,6 +15,7 @@
> >  #include <linux/module.h>
> >  #include <linux/of.h>
> >  #include <linux/of_device.h>
> > +#include <linux/pm_runtime.h>
> >  #include <linux/reset.h>
> >  #include <linux/sizes.h>
> >
> > @@ -548,9 +549,13 @@ static int dwcmshc_probe(struct platform_device
> *pdev)
> >
> >         host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
> >
> > +       pm_runtime_get_noresume(dev);
> > +       pm_runtime_set_active(dev);
> > +       pm_runtime_enable(dev);
> > +
> >         err = sdhci_setup_host(host);
> >         if (err)
> > -               goto err_clk;
> > +               goto err_rpm;
> >
> >         if (rk_priv)
> >                 dwcmshc_rk35xx_postinit(host, priv);
> > @@ -559,10 +564,15 @@ static int dwcmshc_probe(struct platform_device
> *pdev)
> >         if (err)
> >                 goto err_setup_host;
> >
> > +       pm_runtime_put_sync(dev);
> > +
> 
> The async pm_runtime_put() is probably sufficient - and it would allow
> the probe to complete a bit "sooner".

Sure, will test and update the line in v7.

> 
> >         return 0;
> >
> >  err_setup_host:
> >         sdhci_cleanup_host(host);
> > +err_rpm:
> > +       pm_runtime_disable(dev);
> > +       pm_runtime_put_noidle(dev);
> >  err_clk:
> >         clk_disable_unprepare(pltfm_host->clk);
> >         clk_disable_unprepare(priv->bus_clk);
> > @@ -606,6 +616,12 @@ static int dwcmshc_suspend(struct device *dev)
> >         if (ret)
> >                 return ret;
> >
> > +       ret = pm_runtime_force_suspend(dev);
> 
> Can dwcmshc_suspend() be called for a device that may be attached to
> the ACPI PM domain?

BlueField SoC is the only chip that uses ACPI in this driver for now and it doesn't support System Sleep. Thus, the dwcmshc_suspend() won't be called. But I guess it might be possible when other new chip support is added into this driver. Is it a concern?

> 
> > +       if (ret) {
> > +               sdhci_resume_host(host);
> > +               return ret;
> > +       }
> > +
> >         clk_disable_unprepare(pltfm_host->clk);
> >         if (!IS_ERR(priv->bus_clk))
> >                 clk_disable_unprepare(priv->bus_clk);
> > @@ -625,6 +641,10 @@ static int dwcmshc_resume(struct device *dev)
> >         struct rk35xx_priv *rk_priv = priv->priv;
> >         int ret;
> >
> > +       ret = pm_runtime_force_resume(dev);
> > +       if (ret)
> > +               return ret;
> > +
> >         ret = clk_prepare_enable(pltfm_host->clk);
> >         if (ret)
> >                 return ret;
> > @@ -646,7 +666,55 @@ static int dwcmshc_resume(struct device *dev)
> >  }
> >  #endif
> >
> > -static SIMPLE_DEV_PM_OPS(dwcmshc_pmops, dwcmshc_suspend,
> dwcmshc_resume);
> > +#ifdef CONFIG_PM
> > +
> > +static void dwcmshc_enable_card_clk(struct sdhci_host *host)
> > +{
> > +       u16 ctrl;
> > +
> > +       ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> > +       if ((ctrl & SDHCI_CLOCK_INT_EN) && !(ctrl & SDHCI_CLOCK_CARD_EN))
> {
> > +               ctrl |= SDHCI_CLOCK_CARD_EN;
> > +               sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
> > +       }
> > +}
> > +
> > +static void dwcmshc_disable_card_clk(struct sdhci_host *host)
> > +{
> > +       u16 ctrl;
> > +
> > +       ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> > +       if (ctrl & SDHCI_CLOCK_CARD_EN) {
> > +               ctrl &= ~SDHCI_CLOCK_CARD_EN;
> > +               sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
> > +       }
> > +}
> > +
> > +static int dwcmshc_runtime_suspend(struct device *dev)
> > +{
> > +       struct sdhci_host *host = dev_get_drvdata(dev);
> > +
> > +       dwcmshc_disable_card_clk(host);
> > +
> > +       return 0;
> > +}
> > +
> > +static int dwcmshc_runtime_resume(struct device *dev)
> > +{
> > +       struct sdhci_host *host = dev_get_drvdata(dev);
> > +
> > +       dwcmshc_enable_card_clk(host);
> > +
> > +       return 0;
> > +}
> > +
> > +#endif
> > +
> > +static const struct dev_pm_ops dwcmshc_pmops = {
> > +       SET_SYSTEM_SLEEP_PM_OPS(dwcmshc_suspend, dwcmshc_resume)
> > +       SET_RUNTIME_PM_OPS(dwcmshc_runtime_suspend,
> > +                          dwcmshc_runtime_resume, NULL)
> > +};
> >
> >  static struct platform_driver sdhci_dwcmshc_driver = {
> >         .driver = {
> > --
> 
> Kind regards
> Uffe

On Tue, 8 Aug 2023 at 15:21, Liming Sun <limings@nvidia.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Ulf Hansson <ulf.hansson@linaro.org>
> > Sent: Tuesday, August 8, 2023 5:40 AM
> > To: Liming Sun <limings@nvidia.com>
> > Cc: Adrian Hunter <adrian.hunter@intel.com>; David Thompson
> > <davthompson@nvidia.com>; Shawn Lin <shawn.lin@rock-chips.com>; linux-
> > mmc@vger.kernel.org; linux-kernel@vger.kernel.org
> > Subject: Re: [PATCH v6] mmc: sdhci-of-dwcmshc: Add runtime PM operations
> >
> > On Sat, 5 Aug 2023 at 01:30, Liming Sun <limings@nvidia.com> wrote:
> > >
> > > This commit implements the runtime PM operations to disable eMMC
> > > card clock when idle.
> > >
> > > Reviewed-by: David Thompson <davthompson@nvidia.com>
> > > Signed-off-by: Liming Sun <limings@nvidia.com>
> > > ---
> > > v5->v6:
> > >     - Address Adrian's more comments and add coordination between
> > >       runtime PM and system PM;
> > > v4->v5:
> > >     - Address Adrian's comment to move the pm_enable to the end to
> > >       avoid race;
> > > v3->v4:
> > >     - Fix compiling reported by 'kernel test robot';
> > > v2->v3:
> > >     - Revise the commit message;
> > > v1->v2:
> > >     Updates for comments from Ulf:
> > >     - Make the runtime PM logic generic for sdhci-of-dwcmshc;
> > > v1: Initial version.
> > > ---
> > >  drivers/mmc/host/sdhci-of-dwcmshc.c | 72
> > ++++++++++++++++++++++++++++-
> > >  1 file changed, 70 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-
> > of-dwcmshc.c
> > > index e68cd87998c8..aaf66358f626 100644
> > > --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> > > +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> > > @@ -15,6 +15,7 @@
> > >  #include <linux/module.h>
> > >  #include <linux/of.h>
> > >  #include <linux/of_device.h>
> > > +#include <linux/pm_runtime.h>
> > >  #include <linux/reset.h>
> > >  #include <linux/sizes.h>
> > >
> > > @@ -548,9 +549,13 @@ static int dwcmshc_probe(struct platform_device
> > *pdev)
> > >
> > >         host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
> > >
> > > +       pm_runtime_get_noresume(dev);
> > > +       pm_runtime_set_active(dev);
> > > +       pm_runtime_enable(dev);
> > > +
> > >         err = sdhci_setup_host(host);
> > >         if (err)
> > > -               goto err_clk;
> > > +               goto err_rpm;
> > >
> > >         if (rk_priv)
> > >                 dwcmshc_rk35xx_postinit(host, priv);
> > > @@ -559,10 +564,15 @@ static int dwcmshc_probe(struct platform_device
> > *pdev)
> > >         if (err)
> > >                 goto err_setup_host;
> > >
> > > +       pm_runtime_put_sync(dev);
> > > +
> >
> > The async pm_runtime_put() is probably sufficient - and it would allow
> > the probe to complete a bit "sooner".
>
> Sure, will test and update the line in v7.
>
> >
> > >         return 0;
> > >
> > >  err_setup_host:
> > >         sdhci_cleanup_host(host);
> > > +err_rpm:
> > > +       pm_runtime_disable(dev);
> > > +       pm_runtime_put_noidle(dev);
> > >  err_clk:
> > >         clk_disable_unprepare(pltfm_host->clk);
> > >         clk_disable_unprepare(priv->bus_clk);
> > > @@ -606,6 +616,12 @@ static int dwcmshc_suspend(struct device *dev)
> > >         if (ret)
> > >                 return ret;
> > >
> > > +       ret = pm_runtime_force_suspend(dev);
> >
> > Can dwcmshc_suspend() be called for a device that may be attached to
> > the ACPI PM domain?
>
> BlueField SoC is the only chip that uses ACPI in this driver for now and it doesn't support System Sleep. Thus, the dwcmshc_suspend() won't be called. But I guess it might be possible when other new chip support is added into this driver. Is it a concern?

The ACPI PM domain doesn't support drivers using
pm_runtime_force_suspend|resume(). Unless that has been changed
without me knowing about it.

Anyway, it looks like it shouldn't be a problem at this point. We can
also add separate callbacks for other SoCs, if that comes into play
going forward.

[...]

Kind regards
Uffe

> -----Original Message-----
> From: Ulf Hansson <ulf.hansson@linaro.org>
> Sent: Tuesday, August 8, 2023 9:57 AM
> To: Liming Sun <limings@nvidia.com>
> Cc: Adrian Hunter <adrian.hunter@intel.com>; David Thompson
> <davthompson@nvidia.com>; Shawn Lin <shawn.lin@rock-chips.com>; linux-
> mmc@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v6] mmc: sdhci-of-dwcmshc: Add runtime PM operations
> 
> On Tue, 8 Aug 2023 at 15:21, Liming Sun <limings@nvidia.com> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Ulf Hansson <ulf.hansson@linaro.org>
> > > Sent: Tuesday, August 8, 2023 5:40 AM
> > > To: Liming Sun <limings@nvidia.com>
> > > Cc: Adrian Hunter <adrian.hunter@intel.com>; David Thompson
> > > <davthompson@nvidia.com>; Shawn Lin <shawn.lin@rock-chips.com>;
> linux-
> > > mmc@vger.kernel.org; linux-kernel@vger.kernel.org
> > > Subject: Re: [PATCH v6] mmc: sdhci-of-dwcmshc: Add runtime PM
> operations
> > >
> > > On Sat, 5 Aug 2023 at 01:30, Liming Sun <limings@nvidia.com> wrote:
> > > >
> > > > This commit implements the runtime PM operations to disable eMMC
> > > > card clock when idle.
> > > >
> > > > Reviewed-by: David Thompson <davthompson@nvidia.com>
> > > > Signed-off-by: Liming Sun <limings@nvidia.com>
> > > > ---
> > > > v5->v6:
> > > >     - Address Adrian's more comments and add coordination between
> > > >       runtime PM and system PM;
> > > > v4->v5:
> > > >     - Address Adrian's comment to move the pm_enable to the end to
> > > >       avoid race;
> > > > v3->v4:
> > > >     - Fix compiling reported by 'kernel test robot';
> > > > v2->v3:
> > > >     - Revise the commit message;
> > > > v1->v2:
> > > >     Updates for comments from Ulf:
> > > >     - Make the runtime PM logic generic for sdhci-of-dwcmshc;
> > > > v1: Initial version.
> > > > ---
> > > >  drivers/mmc/host/sdhci-of-dwcmshc.c | 72
> > > ++++++++++++++++++++++++++++-
> > > >  1 file changed, 70 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c
> b/drivers/mmc/host/sdhci-
> > > of-dwcmshc.c
> > > > index e68cd87998c8..aaf66358f626 100644
> > > > --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> > > > +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> > > > @@ -15,6 +15,7 @@
> > > >  #include <linux/module.h>
> > > >  #include <linux/of.h>
> > > >  #include <linux/of_device.h>
> > > > +#include <linux/pm_runtime.h>
> > > >  #include <linux/reset.h>
> > > >  #include <linux/sizes.h>
> > > >
> > > > @@ -548,9 +549,13 @@ static int dwcmshc_probe(struct
> platform_device
> > > *pdev)
> > > >
> > > >         host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
> > > >
> > > > +       pm_runtime_get_noresume(dev);
> > > > +       pm_runtime_set_active(dev);
> > > > +       pm_runtime_enable(dev);
> > > > +
> > > >         err = sdhci_setup_host(host);
> > > >         if (err)
> > > > -               goto err_clk;
> > > > +               goto err_rpm;
> > > >
> > > >         if (rk_priv)
> > > >                 dwcmshc_rk35xx_postinit(host, priv);
> > > > @@ -559,10 +564,15 @@ static int dwcmshc_probe(struct
> platform_device
> > > *pdev)
> > > >         if (err)
> > > >                 goto err_setup_host;
> > > >
> > > > +       pm_runtime_put_sync(dev);
> > > > +
> > >
> > > The async pm_runtime_put() is probably sufficient - and it would allow
> > > the probe to complete a bit "sooner".
> >
> > Sure, will test and update the line in v7.
> >
> > >
> > > >         return 0;
> > > >
> > > >  err_setup_host:
> > > >         sdhci_cleanup_host(host);
> > > > +err_rpm:
> > > > +       pm_runtime_disable(dev);
> > > > +       pm_runtime_put_noidle(dev);
> > > >  err_clk:
> > > >         clk_disable_unprepare(pltfm_host->clk);
> > > >         clk_disable_unprepare(priv->bus_clk);
> > > > @@ -606,6 +616,12 @@ static int dwcmshc_suspend(struct device *dev)
> > > >         if (ret)
> > > >                 return ret;
> > > >
> > > > +       ret = pm_runtime_force_suspend(dev);
> > >
> > > Can dwcmshc_suspend() be called for a device that may be attached to
> > > the ACPI PM domain?
> >
> > BlueField SoC is the only chip that uses ACPI in this driver for now and it
> doesn't support System Sleep. Thus, the dwcmshc_suspend() won't be called.
> But I guess it might be possible when other new chip support is added into this
> driver. Is it a concern?
> 
> The ACPI PM domain doesn't support drivers using
> pm_runtime_force_suspend|resume(). Unless that has been changed
> without me knowing about it.
> 
> Anyway, it looks like it shouldn't be a problem at this point. We can
> also add separate callbacks for other SoCs, if that comes into play
> going forward.

Thanks. So no further changes for now.
Posted v7 (for the other comment).

> 
> [...]
> 
> Kind regards
> Uffe

On Sat, 5 Aug 2023 at 01:30, Liming Sun <limings@nvidia.com> wrote:
>
> This commit implements the runtime PM operations to disable eMMC
> card clock when idle.
>
> Reviewed-by: David Thompson <davthompson@nvidia.com>
> Signed-off-by: Liming Sun <limings@nvidia.com>
> ---
> v5->v6:
>     - Address Adrian's more comments and add coordination between
>       runtime PM and system PM;
> v4->v5:
>     - Address Adrian's comment to move the pm_enable to the end to
>       avoid race;
> v3->v4:
>     - Fix compiling reported by 'kernel test robot';
> v2->v3:
>     - Revise the commit message;
> v1->v2:
>     Updates for comments from Ulf:
>     - Make the runtime PM logic generic for sdhci-of-dwcmshc;
> v1: Initial version.
> ---
>  drivers/mmc/host/sdhci-of-dwcmshc.c | 72 ++++++++++++++++++++++++++++-
>  1 file changed, 70 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index e68cd87998c8..aaf66358f626 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -15,6 +15,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/reset.h>
>  #include <linux/sizes.h>
>
> @@ -548,9 +549,13 @@ static int dwcmshc_probe(struct platform_device *pdev)
>
>         host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
>
> +       pm_runtime_get_noresume(dev);
> +       pm_runtime_set_active(dev);
> +       pm_runtime_enable(dev);
> +
>         err = sdhci_setup_host(host);
>         if (err)
> -               goto err_clk;
> +               goto err_rpm;
>
>         if (rk_priv)
>                 dwcmshc_rk35xx_postinit(host, priv);
> @@ -559,10 +564,15 @@ static int dwcmshc_probe(struct platform_device *pdev)
>         if (err)
>                 goto err_setup_host;
>
> +       pm_runtime_put_sync(dev);
> +
>         return 0;
>
>  err_setup_host:
>         sdhci_cleanup_host(host);
> +err_rpm:
> +       pm_runtime_disable(dev);
> +       pm_runtime_put_noidle(dev);
>  err_clk:
>         clk_disable_unprepare(pltfm_host->clk);
>         clk_disable_unprepare(priv->bus_clk);
> @@ -606,6 +616,12 @@ static int dwcmshc_suspend(struct device *dev)
>         if (ret)
>                 return ret;
>

sdhci_suspend_host() is called a few lines above, which requires the
host to be runtime resumed when called. This may not be the case here.

To fix this there are in principle two options:

1) Call a pm_runtime_get_sync() around here and a corresponding
pm_runtime_put_noidle() somewhere after you have called
pm_runtime_force_suspend().

2) Move away from using sdhci_suspend|resume_host(), but use
sdhci_runtime_suspend|resume_host() instead. This requires some
additional changes, but with the benefit that we can avoid runtime
resuming the device upfront. In this case,
sdhci_runtime_suspend|resume_host() should be called from
dwcmshc_runtime_suspend|resume(). Moreover, we either need to move the
entire clock mgmt from dwcmshc_suspend|resume() into the
dwcmshc_runtime_suspend|resume() or call pm_runtime_get_noresume()
before calling pm_runtime_force_suspend() and pm_runtime_put_noidle()
just after it.

> +       ret = pm_runtime_force_suspend(dev);
> +       if (ret) {
> +               sdhci_resume_host(host);
> +               return ret;
> +       }
> +
>         clk_disable_unprepare(pltfm_host->clk);
>         if (!IS_ERR(priv->bus_clk))
>                 clk_disable_unprepare(priv->bus_clk);
> @@ -625,6 +641,10 @@ static int dwcmshc_resume(struct device *dev)
>         struct rk35xx_priv *rk_priv = priv->priv;
>         int ret;
>
> +       ret = pm_runtime_force_resume(dev);
> +       if (ret)
> +               return ret;
> +
>         ret = clk_prepare_enable(pltfm_host->clk);
>         if (ret)
>                 return ret;
> @@ -646,7 +666,55 @@ static int dwcmshc_resume(struct device *dev)
>  }
>  #endif
>
> -static SIMPLE_DEV_PM_OPS(dwcmshc_pmops, dwcmshc_suspend, dwcmshc_resume);
> +#ifdef CONFIG_PM
> +
> +static void dwcmshc_enable_card_clk(struct sdhci_host *host)
> +{
> +       u16 ctrl;
> +
> +       ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +       if ((ctrl & SDHCI_CLOCK_INT_EN) && !(ctrl & SDHCI_CLOCK_CARD_EN)) {
> +               ctrl |= SDHCI_CLOCK_CARD_EN;
> +               sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
> +       }
> +}
> +
> +static void dwcmshc_disable_card_clk(struct sdhci_host *host)
> +{
> +       u16 ctrl;
> +
> +       ctrl = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +       if (ctrl & SDHCI_CLOCK_CARD_EN) {
> +               ctrl &= ~SDHCI_CLOCK_CARD_EN;
> +               sdhci_writew(host, ctrl, SDHCI_CLOCK_CONTROL);
> +       }
> +}
> +
> +static int dwcmshc_runtime_suspend(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +
> +       dwcmshc_disable_card_clk(host);
> +
> +       return 0;
> +}
> +
> +static int dwcmshc_runtime_resume(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +
> +       dwcmshc_enable_card_clk(host);
> +
> +       return 0;
> +}
> +
> +#endif
> +
> +static const struct dev_pm_ops dwcmshc_pmops = {
> +       SET_SYSTEM_SLEEP_PM_OPS(dwcmshc_suspend, dwcmshc_resume)
> +       SET_RUNTIME_PM_OPS(dwcmshc_runtime_suspend,
> +                          dwcmshc_runtime_resume, NULL)
> +};
>
>  static struct platform_driver sdhci_dwcmshc_driver = {
>         .driver = {

Kind regards
Uffe