linux-kernel - Re: [PATCH 1/2] mmc: block: Remove error check of hw

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Message-ID: <CAPDyKFpvsDoLherwwyR5f7oJ0Fdwu6HV0MLgX+DrHkXkQrwbLQ@mail.gmail.com>
Date:   Fri, 7 Oct 2022 15:05:57 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Christian Löhle <CLoehle@...erstone.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Linux MMC List <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mmc: block: Remove error check of hw_reset on reset

On Thu, 6 Oct 2022 at 15:38, Christian Löhle <CLoehle@...erstone.com> wrote:
>
> Before switching back to the right partition in mmc_blk_reset
> there used to be a check if hw_reset was even supported.
> This return value was removed, so there is no reason to check.
>
> Fixes: fefdd3c91e0a ("mmc: core: Drop superfluous validations in mmc_hw|sw_reset()")
> Cc: stable@...r.kernel.org
>
> Signed-off-by: Christian Loehle <cloehle@...erstone.com>
> ---
>  drivers/mmc/core/block.c | 24 ++++++++++--------------
>  1 file changed, 10 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index ce89611a136e..8531f92fd0cb 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -991,6 +991,8 @@ static int mmc_blk_reset(struct mmc_blk_data *md, struct mmc_host *host,
>                          int type)
>  {
>         int err;
> +       struct mmc_blk_data *main_md = dev_get_drvdata(&host->card->dev);
> +       int part_err;
>
>         if (md->reset_done & type)
>                 return -EEXIST;
> @@ -998,20 +1000,14 @@ static int mmc_blk_reset(struct mmc_blk_data *md, struct mmc_host *host,
>         md->reset_done |= type;
>         err = mmc_hw_reset(host->card);
>         /* Ensure we switch back to the correct partition */
> -       if (err) {
> -               struct mmc_blk_data *main_md =
> -                       dev_get_drvdata(&host->card->dev);
> -               int part_err;
> -
> -               main_md->part_curr = main_md->part_type;
> -               part_err = mmc_blk_part_switch(host->card, md->part_type);
> -               if (part_err) {
> -                       /*
> -                        * We have failed to get back into the correct
> -                        * partition, so we need to abort the whole request.
> -                        */
> -                       return -ENODEV;
> -               }

Yes, this is certainly restoring the behaviour and fixing a bug. Thanks!

However, I do wonder about what's the point of trying to switch back
to the correct partition if the mmc_hw_reset() failed (returned a
negative error code). It looks like that shouldn't matter, if the
reset failed we are screwed anyway, right?

> +       main_md->part_curr = main_md->part_type;
> +       part_err = mmc_blk_part_switch(host->card, md->part_type);
> +       if (part_err) {
> +               /*
> +                * We have failed to get back into the correct
> +                * partition, so we need to abort the whole request.
> +                */
> +               return -ENODEV;
>         }
>         return err;
>  }

Kind regards
Uffe