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

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Date:	Thu, 25 Feb 2016 10:49:12 +0100
From:	Ludovic Desroches <ludovic.desroches@...el.com>
To:	<ulf.hansson@...aro.org>
CC:	<linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<nicolas.ferre@...el.com>, <adrian.hunter@...el.com>,
	Ludovic Desroches <ludovic.desroches@...el.com>
Subject: Re: [PATCH] mmc: sdhci-of-at91: fix wakeup issue when using runtime
 pm

On Sat, Feb 13, 2016 at 10:56:40AM +0100, Ludovic Desroches wrote:
> When suspending the sdhci host, the only hardware event that could wake
> up the host is a sdio irq if they are enabled. If we want to wakeup on
> card detect events, a gpio as to be used.
> If we don't want to use a gpio but the card detect pio of the controller
> then we need to keep enabled the clock of the controller interface to
> get the interrupt and to not set the host in a suspended state to have the
> interrupt handled.
> 

How can I move forward on this topic? I have several issues related to
runtime PM (card detection, wifi module which doesn't like to get clocks
disabled) but I am not in favour to get rid of it.

Regards

Ludovic

> Signed-off-by: Ludovic Desroches <ludovic.desroches@...el.com>
> ---
>  drivers/mmc/host/sdhci-of-at91.c | 46 ++++++++++++++++++++++++++++++----------
>  1 file changed, 35 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> index efec736..2159c6e 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>
> @@ -45,7 +46,6 @@ static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
>  
>  static const struct sdhci_pltfm_data soc_data_sama5d2 = {
>  	.ops = &sdhci_at91_sama5d2_ops,
> -	.quirks = SDHCI_QUIRK_BROKEN_CARD_DETECTION,
>  	.quirks2 = SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST,
>  };
>  
> @@ -55,17 +55,37 @@ static const struct of_device_id sdhci_at91_dt_match[] = {
>  };
>  
>  #ifdef CONFIG_PM
> +static bool sdhci_at91_use_sdhci_runtime(struct sdhci_host *host)
> +{
> +	u32 caps = host->mmc->caps;
> +
> +	return (caps & MMC_CAP_NONREMOVABLE) ||
> +	       (!IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc)));
> +}
> +
>  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;
> +	int ret = 0;
>  
> -	ret = sdhci_runtime_suspend_host(host);
> +	/*
> +	 * If we call sdhci_runtime_suspend(), we could wakeup only if sdio
> +	 * irqs are enabled. If we want to wakeup on a card detect event there
> +	 * are two options:
> +	 * - do not call sdhci_runtime_suspend() but save power by disabling
> +	 *   all clocks excepting the one for the controller interface.
> +	 * - call sdhci_runtime_suspend(), save maximum power by disabling
> +	 *   all clocks but use a gpio for the card detect signal to have a way
> +	 *   to wakeup.
> +	 */
> +	if (sdhci_at91_use_sdhci_runtime(host)) {
> +		ret = sdhci_runtime_suspend_host(host);
> +		clk_disable_unprepare(priv->hclock);
> +	}
>  
>  	clk_disable_unprepare(priv->gck);
> -	clk_disable_unprepare(priv->hclock);
>  	clk_disable_unprepare(priv->mainck);
>  
>  	return ret;
> @@ -84,19 +104,23 @@ static int sdhci_at91_runtime_resume(struct device *dev)
>  		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);
> +	if (sdhci_at91_use_sdhci_runtime(host)) {
> +		ret = clk_prepare_enable(priv->hclock);
> +		if (ret) {
> +			dev_err(dev, "can't enable hclock\n");
> +			return ret;
> +		}
> +
> +		ret = sdhci_runtime_resume_host(host);
> +	}
> +
> +	return ret;
>  }
>  #endif /* CONFIG_PM */
>  
> -- 
> 2.7.0
>