linux-kernel - Re: [PATCH v3] mmc: sdhci at91: add PM support

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Date:	Tue, 10 Nov 2015 15:03:57 +0100
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Ludovic Desroches <ludovic.desroches@...el.com>
Cc:	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3] mmc: sdhci at91: add PM support

On 10 November 2015 at 14:23, Ludovic Desroches
<ludovic.desroches@...el.com> wrote:
> Add runtime PM support and use runtime_force_suspend|resume() for system
> PM.
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches@...el.com>
> ---
>
> Changes:
> - from v2: cleanup thanks to Ulf feedback
> - from v1: take a runtime PM centric approach
>
>  drivers/mmc/host/sdhci-of-at91.c | 67 +++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 66 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> index 06d0b50..bbac18e 100644
> --- a/drivers/mmc/host/sdhci-of-at91.c
> +++ b/drivers/mmc/host/sdhci-of-at91.c
> @@ -21,6 +21,8 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/pm.h>
> +#include <linux/pm_runtime.h>
>
>  #include "sdhci-pltfm.h"
>
> @@ -51,6 +53,60 @@ static const struct of_device_id sdhci_at91_dt_match[] = {
>         {}
>  };
>
> +#ifdef CONFIG_PM
> +static int sdhci_at91_runtime_suspend(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +       struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +       struct sdhci_at91_priv *priv = pltfm_host->priv;
> +       int ret;
> +
> +       ret = sdhci_runtime_suspend_host(host);
> +
> +       clk_disable_unprepare(priv->gck);
> +       clk_disable_unprepare(priv->hclock);
> +       clk_disable_unprepare(priv->mainck);
> +
> +       return ret;
> +}
> +
> +static int sdhci_at91_runtime_resume(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +       struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +       struct sdhci_at91_priv *priv = pltfm_host->priv;
> +       int ret;
> +
> +       ret = clk_prepare_enable(priv->mainck);
> +       if (ret) {
> +               dev_err(dev, "can't enable mainck\n");
> +               return ret;
> +       }
> +
> +       ret = clk_prepare_enable(priv->hclock);
> +       if (ret) {
> +               dev_err(dev, "can't enable hclock\n");
> +               return ret;
> +       }
> +
> +       ret = clk_prepare_enable(priv->gck);
> +       if (ret) {
> +               dev_err(dev, "can't enable gck\n");
> +               return ret;
> +       }
> +
> +       return sdhci_runtime_resume_host(host);
> +}
> +#endif /* CONFIG_PM */
> +
> +static const struct dev_pm_ops sdhci_at91_dev_pm_ops = {
> +       SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +                               pm_runtime_force_resume)
> +       SET_RUNTIME_PM_OPS(sdhci_at91_runtime_suspend,
> +                          sdhci_at91_runtime_resume,
> +                          NULL)
> +};
> +
>  static int sdhci_at91_probe(struct platform_device *pdev)
>  {
>         const struct of_device_id       *match;
> @@ -144,6 +200,11 @@ static int sdhci_at91_probe(struct platform_device *pdev)
>
>         sdhci_get_of_property(pdev);
>
> +       pm_runtime_set_active(&pdev->dev);
> +       pm_runtime_enable(&pdev->dev);
> +       pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
> +       pm_runtime_use_autosuspend(&pdev->dev);
> +
>         ret = sdhci_add_host(host);
>         if (ret)
>                 goto clocks_disable_unprepare;

You need to add error handling of runtime PM after this point.

Typically:
pm_runtime_disable() and pm_runtime_set_suspended() needs to be done.

> @@ -165,6 +226,10 @@ static int sdhci_at91_remove(struct platform_device *pdev)
>         struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>         struct sdhci_at91_priv  *priv = pltfm_host->priv;
>
> +       pm_runtime_get_sync(&pdev->dev);
> +       pm_runtime_disable(&pdev->dev);
> +       pm_runtime_put_noidle(&pdev->dev);
> +
>         sdhci_pltfm_unregister(pdev);
>
>         clk_disable_unprepare(priv->gck);
> @@ -178,7 +243,7 @@ static struct platform_driver sdhci_at91_driver = {
>         .driver         = {
>                 .name   = "sdhci-at91",
>                 .of_match_table = sdhci_at91_dt_match,
> -               .pm     = SDHCI_PLTFM_PMOPS,
> +               .pm     = &sdhci_at91_dev_pm_ops,
>         },
>         .probe          = sdhci_at91_probe,
>         .remove         = sdhci_at91_remove,
> --
> 2.5.0
>

Kind regards
Uffe
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