RE: [PATCH v4] mmc: sdhci-of-dwcmshc: Add runtime PM operations

[Liming Sun]

Done, updated in v5.
(sorry, not sure how I missed this comment earlier).

> -----Original Message-----
> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Sent: Friday, May 19, 2023 9:19 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 v4] mmc: sdhci-of-dwcmshc: Add runtime PM operations
> 
> On 12/05/23 21:15, 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>
> > ---
> > 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 | 54
> ++++++++++++++++++++++++++++-
> >  1 file changed, 53 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-
> of-dwcmshc.c
> > index e68cd87998c8..2d780a5bc8fb 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>
> >
> > @@ -546,6 +547,8 @@ static int dwcmshc_probe(struct platform_device
> *pdev)
> >  		sdhci_enable_v4_mode(host);
> >  #endif
> >
> > +	pm_runtime_enable(dev);
> 
> Is there a reason to call it this early?  That raises questions
> about runtime PM racing with the rest of the host initialization.
> Perhaps below instead (note also using devm):
> 
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-
> of-dwcmshc.c
> index 2d780a5bc8fb..5cee42d72257 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -547,8 +547,6 @@ static int dwcmshc_probe(struct platform_device
> *pdev)
>  		sdhci_enable_v4_mode(host);
>  #endif
> 
> -	pm_runtime_enable(dev);
> -
>  	host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
> 
>  	err = sdhci_setup_host(host);
> @@ -562,6 +560,8 @@ static int dwcmshc_probe(struct platform_device
> *pdev)
>  	if (err)
>  		goto err_setup_host;
> 
> +	devm_pm_runtime_enable(dev);
> +
>  	return 0;
> 
>  err_setup_host:
> 
> 
> > +
> >  	host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
> >
> >  	err = sdhci_setup_host(host);
> > @@ -646,7 +649,56 @@ 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);
> > +	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);
> > +	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);
> > +	int ret = 0;
> > +
> > +	ret = sdhci_runtime_suspend_host(host);
> > +	if (!ret)
> > +		dwcmshc_disable_card_clk(host);
> > +
> > +	return ret;
> > +}
> > +
> > +static int dwcmshc_runtime_resume(struct device *dev)
> > +{
> > +	struct sdhci_host *host = dev_get_drvdata(dev);
> > +	int ret = 0;
> > +
> > +	dwcmshc_enable_card_clk(host);
> > +	ret = sdhci_runtime_resume_host(host, 0);
> > +
> > +	return ret;
> > +}
> > +
> > +#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	= {