[PATCH v3 2/3] mmc: sdhci-of-dwcmshc: Add runtime PM support

[Ulf Hansson]

On Thu, 2 Feb 2023 at 01:35, Shawn Lin <shawn.lin at rock-chips.com> wrote:
>
> This patch adds runtime PM support.
>
> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
> ---
>
> Changes in v2: None
>
>  drivers/mmc/host/sdhci-of-dwcmshc.c | 51 ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index 46b1ce7..fc917ed 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>
>
> @@ -551,6 +552,13 @@ static int dwcmshc_probe(struct platform_device *pdev)
>         if (err)
>                 goto err_setup_host;
>
> +       pm_runtime_get_noresume(&pdev->dev);
> +       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);
> +       pm_runtime_put_autosuspend(&pdev->dev);
> +
>         return 0;
>
>  err_setup_host:
> @@ -580,6 +588,11 @@ static int dwcmshc_remove(struct platform_device *pdev)
>         if (rk_priv)
>                 clk_bulk_disable_unprepare(RK35xx_MAX_CLKS,
>                                            rk_priv->rockchip_clks);
> +
> +       pm_runtime_get_sync(&pdev->dev);
> +       pm_runtime_disable(&pdev->dev);
> +       pm_runtime_put_noidle(&pdev->dev);
> +
>         sdhci_pltfm_free(pdev);
>
>         return 0;
> @@ -638,7 +651,43 @@ static int dwcmshc_resume(struct device *dev)
>  }
>  #endif
>
> -static SIMPLE_DEV_PM_OPS(dwcmshc_pmops, dwcmshc_suspend, dwcmshc_resume);
> +#ifdef CONFIG_PM
> +static int dwcmshc_runtime_suspend(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +       u16 data;
> +       int ret;
> +
> +       ret = sdhci_runtime_suspend_host(host);
> +       if (ret)
> +               return ret;
> +
> +       data = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +       data &= ~SDHCI_CLOCK_CARD_EN;
> +       sdhci_writew(host, data, SDHCI_CLOCK_CONTROL);
> +
> +       return 0;
> +}
> +
> +static int dwcmshc_runtime_resume(struct device *dev)
> +{
> +       struct sdhci_host *host = dev_get_drvdata(dev);
> +       u16 data;
> +
> +       data = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +       data |= SDHCI_CLOCK_CARD_EN;
> +       sdhci_writew(host, data, SDHCI_CLOCK_CONTROL);
> +
> +       return sdhci_runtime_resume_host(host, 0);
> +}
> +#endif
> +
> +static const struct dev_pm_ops dwcmshc_pmops = {
> +       SET_SYSTEM_SLEEP_PM_OPS(dwcmshc_suspend,
> +                               dwcmshc_resume)

I have looked at dwcmshc_suspend(), which calls sdhci_suspend_host().
As sdhci_suspend_host() will write to internal registers of the IP
block, it's recommended to make sure the device's runtime resumed
before doing that call. So that needs to be added along with $subject
patch.

There is also another option that may better for you, which is to use
the pm_runtime_force_suspend|resume() helpers. There should be plenty
of references to look at, but don't hesitate to ask around that, if
you need some more help to get that working.

> +       SET_RUNTIME_PM_OPS(dwcmshc_runtime_suspend,
> +                          dwcmshc_runtime_resume, NULL)
> +};
>
>  static struct platform_driver sdhci_dwcmshc_driver = {
>         .driver = {

Kind regards
Uffe