RE: [PATCH v8] mmc: sdhci-of-dwcmshc: Add runtime PM operations

[Liming Sun]

> -----Original Message-----
> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Sent: Thursday, August 17, 2023 3:36 AM
> To: Liming Sun <limings@xxxxxxxxxx>; Ulf Hansson <ulf.hansson@xxxxxxxxxx>;
> David Thompson <davthompson@xxxxxxxxxx>; Shawn Lin <shawn.lin@rock-
> chips.com>
> Cc: linux-mmc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v8] mmc: sdhci-of-dwcmshc: Add runtime PM operations
> 
> On 17/08/23 04:06, Liming Sun wrote:
> > This commit implements the runtime PM operations to disable eMMC
> > card clock when idle.
> >
> > Reviewed-by: David Thompson <davthompson@xxxxxxxxxx>
> > Signed-off-by: Liming Sun <limings@xxxxxxxxxx>
> > ---
> > v7->v8:
> >     - Address Ulf's comment (option-1);
> >     - Updates for Adrian;s comment to remove the force_suspend/resume
> >       in dwcmshc_resume()/dwcmshc_suspend(); Add comments for
> >       dwcmshc_resume()/dwcmshc_suspend();
> > v6->v7:
> >     - Address Ulf's comment;
> > 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 | 76
> +++++++++++++++++++++++++++--
> >  1 file changed, 73 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-
> of-dwcmshc.c
> > index e68cd87998c8..2196218c9d79 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(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);
> > @@ -594,6 +604,10 @@ static int dwcmshc_remove(struct platform_device
> *pdev)
> >  }
> >
> >  #ifdef CONFIG_PM_SLEEP
> > +/*
> > + * Note, runtime suspend changes only SDHCI_CLOCK_CARD_EN which has
> no effect on
> > + * system suspend.
> > + */
> 
> This comment isn't needed since pm_runtime_get_sync() will
> always runtime resume the device if needed.

Updated in v9.

> 
> >  static int dwcmshc_suspend(struct device *dev)
> >  {
> >  	struct sdhci_host *host = dev_get_drvdata(dev);
> > @@ -602,9 +616,11 @@ static int dwcmshc_suspend(struct device *dev)
> >  	struct rk35xx_priv *rk_priv = priv->priv;
> >  	int ret;
> >
> > +	pm_runtime_get_sync(dev);
> 
> This needs a corresponding pm_runtime_put() at the end of
> dwcmshc_resume().

Updated in v9.

> 
> > +
> >  	ret = sdhci_suspend_host(host);
> >  	if (ret)
> > -		return ret;
> > +		goto err_suspend;
> >
> >  	clk_disable_unprepare(pltfm_host->clk);
> >  	if (!IS_ERR(priv->bus_clk))
> > @@ -614,9 +630,15 @@ static int dwcmshc_suspend(struct device *dev)
> >  		clk_bulk_disable_unprepare(RK35xx_MAX_CLKS,
> >  					   rk_priv->rockchip_clks);
> >
> > +err_suspend:
> > +	pm_runtime_put_noidle(dev);
> >  	return ret;
> >  }
> >
> > +/*
> > + * Note, system resume leaves SDHCI_CLOCK_INT_EN off which is consistent
> with
> > + * either runtime suspended or runtime resumed.
> > + */
> 
> As above, this comment isn't needed.

Updated in v9.

> 
> >  static int dwcmshc_resume(struct device *dev)
> 
> 
> As mentioned above, dwcmshc_resume() needs a pm_runtime_put()
> to balance the pm_runtime_get_sync().

Updated in v9.

> 
> Could fix up the error path too, but that should be a
> separate prior patch.
> 
> Probably end up looking like:
> 
> 
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-
> of-dwcmshc.c
> index 20aa9b6327d2..c9b020b7a3f6 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -652,17 +652,33 @@ static int dwcmshc_resume(struct device *dev)
>  	if (!IS_ERR(priv->bus_clk)) {
>  		ret = clk_prepare_enable(priv->bus_clk);
>  		if (ret)
> -			return ret;
> +			goto disable_clk;
>  	}
> 
>  	if (rk_priv) {
>  		ret = clk_bulk_prepare_enable(RK35xx_MAX_CLKS,
>  					      rk_priv->rockchip_clks);
>  		if (ret)
> -			return ret;
> +			goto disable_bus_clk;
>  	}
> 
> -	return sdhci_resume_host(host);
> +	ret = sdhci_resume_host(host);
> +	if (ret)
> +		goto disable_rockchip_clks;
> +
> +	pm_runtime_put(dev);
> +
> +	return 0;
> +
> +disable_rockchip_clks:
> +	if (rk_priv)
> +		clk_bulk_disable_unprepare(RK35xx_MAX_CLKS, rk_priv-
> >rockchip_clks);
> +disable_bus_clk:
> +	if (!IS_ERR(priv->bus_clk))
> +		clk_disable_unprepare(priv->bus_clk);
> +disable_clk:
> +	clk_disable_unprepare(pltfm_host->clk);
> +	return ret;
>  }
>  #endif
> 
> 

Do you mean a separate 'post' patch? I left it out in v9 and could post another one for this error path. Or do you prefer the same patch series?

> 
> 
> >  {
> >  	struct sdhci_host *host = dev_get_drvdata(dev);
> > @@ -646,7 +668,55 @@ 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	= {