linux-kernel - Re: [PATCH] mmc: core: add a power cycle when CMD11 fails

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Message-ID: <CAPDyKFpQyoNELdh3FrFF++HXKjH_Tn9oaY=PzUXHcE8o=KK-hg@mail.gmail.com>
Date:   Tue, 2 Mar 2021 11:38:40 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     DooHyun Hwang <dh0421.hwang@...sung.com>
Cc:     "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Eric Biggers <ebiggers@...gle.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Satya Tangirala <satyat@...gle.com>,
        Ludovic Barre <ludovic.barre@...com>,
        Linus Walleij <linus.walleij@...aro.org>,
        grant.jung@...sung.com, jt77.jang@...sung.com,
        junwoo80.lee@...sung.com, jangsub.yi@...sung.com,
        sh043.lee@...sung.com, Chanwoo Lee <cw9316.lee@...sung.com>,
        sh8267.baek@...sung.com, wkon.kim@...sung.com
Subject: Re: [PATCH] mmc: core: add a power cycle when CMD11 fails

On Wed, 10 Feb 2021 at 06:12, DooHyun Hwang <dh0421.hwang@...sung.com> wrote:
>
> A power cycle is required if CMD11 fails.
> CMD11 failure should be handled as no response.
>
> If there is a timeout error that means no response to the CMD11,
> do not send the CMD11 again and the power cycle is required.
> Any other errors for CMD11 are the same because CMD11 failed.
>
> On some bad SD Card, CMD11 may fail but the card may have already
> invoked the voltage switch sequence.
> In this case, it is necessary to retry without voltage switching
> after power cycle.
>
> Signed-off-by: DooHyun Hwang <dh0421.hwang@...sung.com>

Applied for next, thanks!

I took the liberty of updating the commit message a bit, to try to
clarify things. Moreover, I have tagged this for stable kernels.

BTW, did you try to force the error to -EAGAIN, to keep retrying for a
couple of times? If so, did it end up with the same kind of errors?

> ---
>  drivers/mmc/core/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 1136b859ddd8..a6674df2a7bb 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1207,7 +1207,7 @@ int mmc_set_uhs_voltage(struct mmc_host *host, u32 ocr)
>
>         err = mmc_wait_for_cmd(host, &cmd, 0);
>         if (err)
> -               return err;
> +               goto power_cycle;
>
>         if (!mmc_host_is_spi(host) && (cmd.resp[0] & R1_ERROR))
>                 return -EIO;
> --
> 2.29.0
>

Kind regards
Uffe