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

Ulf Hansson
2023-08-08T16:51:18Z

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