On 20 April 2016 at 18:51, Dong Aisheng <aisheng.dong@xxxxxxx> 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@xxxxxxx>
> ---
> 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
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