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

Liming Sun
2023-07-28T12:24:09Z

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

> -----Original Message-----
> From: Adrian Hunter <adrian.hunter@intel.com>
> Sent: Friday, May 19, 2023 9:19 AM
> To: Liming Sun <limings@nvidia.com>; Ulf Hansson <ulf.hansson@linaro.org>;
> David Thompson <davthompson@nvidia.com>; Shawn Lin <shawn.lin@rock-
> chips.com>
> Cc: linux-mmc@vger.kernel.org; linux-kernel@vger.kernel.org
> 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@nvidia.com>
> > Signed-off-by: Liming Sun <limings@nvidia.com>
> > ---
> > 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 = {