linux-kernel - Re: [PATCH] mmc: host: sdhci: Fix the incorrect soft reset operation when runtime resuming

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Date:   Mon, 15 Jul 2019 14:19:35 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Baolin Wang <baolin.wang@...aro.org>, ulf.hansson@...aro.org
Cc:     zhang.lyra@...il.com, orsonzhai@...il.com,
        linus.walleij@...aro.org, vincent.guittot@...aro.org,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: host: sdhci: Fix the incorrect soft reset operation
 when runtime resuming

On 15/07/19 1:58 PM, Baolin Wang wrote:
> In sdhci_runtime_resume_host() function, we will always do software reset
> for all, but according to the specification, we should issue reset command
> and reinitialize the SD/eMMC card.

Where does it say that?

>                                    However, we only do reinitialize the
> SD/eMMC card when the SD/eMMC card are power down during runtime suspend.
> 
> Thus for those platforms that do not power down the SD/eMMC card during
> runtime suspend, we should not do software reset for all.
>                                                           To fix this
> issue, we can add one condition to validate the MMC_CAP_AGGRESSIVE_PM
> to decide if we can do software reset for all or just reset command
> and data lines.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
>  drivers/mmc/host/sdhci.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 9715834..470c5e0 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3333,7 +3333,7 @@ int sdhci_runtime_resume_host(struct sdhci_host *host)
>  			host->ops->enable_dma(host);
>  	}
>  
> -	sdhci_init(host, 0);
> +	sdhci_init(host, !(mmc->caps & MMC_CAP_AGGRESSIVE_PM));

We have done a full reset for a long time, so it would be surprising to need
to change it.

What problem is it causing?

>  
>  	if (mmc->ios.power_mode != MMC_POWER_UNDEFINED &&
>  	    mmc->ios.power_mode != MMC_POWER_OFF) {
>