linux-kernel - Re: [PATCH] mmc: sdhci-of-at91: fix wakeup issue when using runtime pm

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Date:	Wed, 16 Mar 2016 12:04:46 +0100
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Ludovic Desroches <ludovic.desroches@...el.com>
Cc:	Adrian Hunter <adrian.hunter@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Kevin Hilman <khilman@...nel.org>,
	Nicolas Ferre <nicolas.ferre@...el.com>
Subject: Re: [PATCH] mmc: sdhci-of-at91: fix wakeup issue when using runtime pm

On 10 March 2016 at 11:30, Ludovic Desroches
<ludovic.desroches@...el.com> wrote:
> It was impossible to wake-up on card detect event because when sdhci
> controller is runtime suspend, it is assumed that all the clocks are
> disabled so we can't get irqs.
> If the device is removable and there is no gpio to manage the card
> detection then card detection polling is used.
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches@...el.com>
> ---
>
> Hi Ulf, Adrian,
>
> Following the discussion, I need to fix my issue. I think we could both agree
> on this patch that I see more as temporary workaround.
>
> I will try to change the muxing of the card detect pio in order to no more
> use the sdhci controller to manage it but a gpio. If it do not work then
> I may send another patch in the spirit of the previous one (keeping one clock
> enabled and not calling sdhci_runtime_suspend_host()).
>
> Regards
>
>  drivers/mmc/host/sdhci-of-at91.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> index 35c02fc..dac8508 100644
> --- a/drivers/mmc/host/sdhci-of-at91.c
> +++ b/drivers/mmc/host/sdhci-of-at91.c
> @@ -18,6 +18,7 @@
>  #include <linux/err.h>
>  #include <linux/io.h>
>  #include <linux/mmc/host.h>
> +#include <linux/mmc/slot-gpio.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> @@ -204,6 +205,21 @@ static int sdhci_at91_probe(struct platform_device *pdev)
>         if (ret)
>                 goto pm_runtime_disable;
>
> +       /*
> +        * When calling sdhci_runtime_suspend_host(), the sdhci layer makes
> +        * the assumption that all the clocks of the controller are disabled.
> +        * It means we can't get irq from it when it is runtime suspended.
> +        * For that reason, it is not planned to wake-up on a card detect irq
> +        * from the controller.
> +        * If we want to use runtime PM and to be able to wake-up on card
> +        * insertion, we have to use a GPIO for the card detection or we can
> +        * use polling for the card detection. Be aware that using polling
> +        * will resume/suspend the controller between each attempt.
> +        */
> +       if (!(host->mmc->caps & MMC_CAP_NONREMOVABLE) &&
> +           IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc)))
> +               host->mmc->caps |= MMC_CAP_NEEDS_POLL;

Perhaps also clearing SDHCI_QUIRK_BROKEN_CARD_DETECTION, as this
doesn't play well if this is set via parsing the DTS.

> +
>         pm_runtime_put_autosuspend(&pdev->dev);
>
>         return 0;
> --
> 2.5.0
>

Otherwise this looks okay to me.

Kind regards
Uffe