linux-kernel - Re: [PATCHv3 1/2] mmc: block: Remove error check of hw

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Date:   Tue, 11 Oct 2022 12:24:36 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Christian Löhle <cloehle@...erstone.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Cc:     Linux MMC List <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv3 1/2] mmc: block: Remove error check of hw_reset on reset

On Tue, 11 Oct 2022 at 12:15, Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 10/10/22 17:03, Christian Löhle 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.
> > Furthermore ensure part_curr is not falsely set to a valid value
> > on reset or partition switch error.
> >
> > 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>
> > ---
> > -v3: Ensure invalid part_curr on error
> > -v2: Do not attempt to switch partitions if reset failed
> >
> >  drivers/mmc/core/block.c | 29 ++++++++++++++---------------
> >  1 file changed, 14 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> > index ce89611a136e..45a44edcc31a 100644
> > --- a/drivers/mmc/core/block.c
> > +++ b/drivers/mmc/core/block.c
> > @@ -134,6 +134,7 @@ struct mmc_blk_data {
> >        * track of the current selected device partition.
> >        */
> >       unsigned int    part_curr;
> > +#define MMC_BLK_PART_INVALID UINT_MAX        /* Unknown partition active */
> >       int     area_type;
> >
> >       /* debugfs files (only in main mmc_blk_data) */
> > @@ -991,29 +992,27 @@ 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;
> >
> >       md->reset_done |= type;
> > +     main_md->part_curr = MMC_BLK_PART_INVALID;
>
> This forces a partition switch even if it is not necessary.

Right, very good point!

>
> >       err = mmc_hw_reset(host->card);
>
> This would be better:
>
>         /*
>          * A successful reset will leave the card in the main partition, but
>          * upon failure it might not be, so set it to MMC_BLK_PART_INVALID
>          * in that case.
>          */
>         main_md->part_curr = err ? MMC_BLK_PART_INVALID : main_md->part_type;
>

Yes! And the comment is valuable too!

[...]

Kind regards
Uffe