[PATCH 1/3] mmc: core: fix using wrong io voltage if mmc_select_hs200 fails

[Ulf Hansson]

On 20 April 2016 at 18:51, Dong Aisheng <aisheng.dong at nxp.com> wrote:
> Currently MMC core will keep going if HS200/HS timing switch failed
> with -EBADMSG error by the assumption that the old timing is still valid.
>
> However, for mmc_select_hs200 case, the signal voltage may have already
> been switched. If the timing switch failed, we should fall back to
> the old voltage in case the card is continue run with legacy timing.
>
> If fall back signal voltage failed, we explicitly report an EIO error
> to force retry during the next power cycle.
>
> Signed-off-by: Dong Aisheng <aisheng.dong at nxp.com>
> ---
>  drivers/mmc/core/mmc.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index b8aa12c..f6683a9 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1245,9 +1245,11 @@ static int mmc_select_hs200(struct mmc_card *card)
>         struct mmc_host *host = card->host;
>         bool send_status = true;
>         unsigned int old_timing;
> +       unsigned int old_signal_voltage;

Nitpick; you can merge this change into the line above.

>         int err = -EINVAL;
>         u8 val;
>
> +       old_signal_voltage = host->ios.signal_voltage;
>         if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200_1_2V)
>                 err = __mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_120);
>
> @@ -1256,7 +1258,7 @@ static int mmc_select_hs200(struct mmc_card *card)
>
>         /* If fails try again during next card power cycle */
>         if (err)
> -               goto err;
> +               return err;
>
>         mmc_select_driver_type(card);
>
> @@ -1290,9 +1292,14 @@ static int mmc_select_hs200(struct mmc_card *card)
>                 }
>         }
>  err:
> -       if (err)
> +       if (err) {
> +               /* fall back to the old signal voltage, if fails report error */
> +               if (__mmc_set_signal_voltage(host, old_signal_voltage))
> +                       err = -EIO;
> +
>                 pr_err("%s: %s failed, error %d\n", mmc_hostname(card->host),
>                        __func__, err);
> +       }
>         return err;
>  }
>
> --
> 1.9.1
>

Kind regards
Uffe