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

Adrian Hunter
2023-08-17T07:36:55Z

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@nvidia.com>
> Signed-off-by: Liming Sun <limings@nvidia.com>
> ---
> 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.

> 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().

> +
> 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.

> static int dwcmshc_resume(struct device *dev)

As mentioned above, dwcmshc_resume() needs a pm_runtime_put()
to balance the pm_runtime_get_sync().

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

> {
> 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 = {