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

Adrian Hunter
2023-05-19T13:19:41Z

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 = {