linux-kernel - Re: [PATCH v2 2/2] mmc: core: fall back host->f_init if failing to init mmc card after resume

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Date:   Sat, 20 Aug 2016 11:02:00 +0800
From:   Shawn Lin <shawn.lin@...k-chips.com>
To:     Shawn Lin <shawn.lin@...k-chips.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     shawn.lin@...k-chips.com, Adrian Hunter <adrian.hunter@...el.com>,
        Jaehoon Chung <jh80.chung@...sung.com>,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Doug Anderson <dianders@...omium.org>,
        linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] mmc: core: fall back host->f_init if failing to
 init mmc card after resume

Hi Ulf,

Any idea to share with this patch? :)

On 2016/7/20 9:57, Shawn Lin wrote:
> We observed the failure of initializing card after resume
> accidentally. It's hard to reproduce but we did get report from
> the suspend/resume test of our RK3399 mp test farm . Unfortunately,
> we still fail to figure out what was going wrong at that time.
> Also we can't achieve it by retrying the host->f_init without falling
> back it. But this patch will solve the problem as we could add some log
> there and see that we resume the mmc card successfully after falling
> back the host->f_init. There is no obvious side effect found, so it seems
> this patch will improve the stability.
>
> [   93.405085] mmc1: unexpected status 0x800900 after switch
> [   93.408474] mmc1: switch to bus width 1 failed
> [   93.408482] mmc1: mmc_select_hs200 failed, error -110
> [   93.408492] mmc1: error -110 during resume (card was removed?)
> [   93.408705] PM: resume of devices complete after 213.453 msecs
>
> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
>
> ---
>
> Changes in v2:
> - remove mmc_power_off
> - take f_min into consideration
>
>  drivers/mmc/core/mmc.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 403b97b..a2891c1 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1945,6 +1945,7 @@ static int mmc_suspend(struct mmc_host *host)
>  static int _mmc_resume(struct mmc_host *host)
>  {
>  	int err = 0;
> +	int i;
>
>  	BUG_ON(!host);
>  	BUG_ON(!host->card);
> @@ -1954,8 +1955,22 @@ static int _mmc_resume(struct mmc_host *host)
>  	if (!mmc_card_suspended(host->card))
>  		goto out;
>
> -	mmc_power_up(host, host->card->ocr);
> -	err = mmc_init_card(host, host->card->ocr, host->card);
> +	/*
> +	 * Let's try to fallback the host->f_init
> +	 * if failing to init mmc card after resume.
> +	 */
> +	for (i = 0; i < ARRAY_SIZE(freqs); i++) {
> +		if (host->f_init < max(freqs[i], host->f_min))
> +			continue;
> +		else
> +			host->f_init = max(freqs[i], host->f_min);
> +
> +		mmc_power_up(host, host->card->ocr);
> +		err = mmc_init_card(host, host->card->ocr, host->card);
> +		if (!err)
> +			break;
> +	}
> +
>  	mmc_card_clr_suspended(host->card);
>
>  out:
>


-- 
Best Regards
Shawn Lin