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

[Adrian Hunter]

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@xxxxxxxxxx>
> Signed-off-by: Liming Sun <limings@xxxxxxxxxx>
> ---
> 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	= {