Re: [PATCH v2 1/2] mmc: core: Fix CMD6 timeout issue

[Yong Mao <yong.mao@mediatek.com>]

On Thu, 2017-01-12 at 11:58 +0100, Ulf Hansson wrote:
> -trimmed cc list
> 
> On 3 January 2017 at 09:49, Yong Mao <yong.mao@mediatek.com> wrote:
> > From: yong mao <yong.mao@mediatek.com>
> >
> > When initializing EMMC, after switch to HS400,
> > it will issue CMD6 to change ext_csd,
> > if first CMD6 got CRC error,
> > the repeat CMD6 may get timeout,
> > that's because card is not back to transfer state immediately.
> >
> > For resolving this issue, it need check if card is busy
> > before sending repeat CMD6.
> >
> > Not only CMD6 here has this issue, but also other R1B CMD has
> > the same issue.
> 
> Is this change still something you want to discuss? Or the issue is resolved by:
> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1308640.html

Yes. we still want to discuss this change with you.
The change in
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1308640.html resolves the other issue.
Please help to review this change and make some comments.
Thanks.

Best Regards,
Yong Mao.
> 
> Kind regards
> Uffe
> 
> >
> > Signed-off-by: Yong Mao <yong.mao@mediatek.com>
> > Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
> > ---
> >  drivers/mmc/core/core.c |   19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> > index 1076b9d..8674dbb 100644
> > --- a/drivers/mmc/core/core.c
> > +++ b/drivers/mmc/core/core.c
> > @@ -566,6 +566,25 @@ void mmc_wait_for_req_done(struct mmc_host *host, struct mmc_request *mrq)
> >
> >                 mmc_retune_recheck(host);
> >
> > +               /*
> > +                * If a R1B CMD such as CMD6 occur CRC error,
> > +                * it will retry 3 times here.
> > +                * But before retrying, it must ensure card is in
> > +                * transfer state.
> > +                * Otherwise, the next retried CMD will got TMO error.
> > +                */
> > +               if (mmc_resp_type(cmd) == MMC_RSP_R1B && host->ops->card_busy) {
> > +                       int tries = 500; /* Wait aprox 500ms at maximum */
> > +
> > +                       while (host->ops->card_busy(host) && --tries)
> > +                               mmc_delay(1);
> > +
> > +                       if (tries == 0) {
> > +                               cmd->error = -EBUSY;
> > +                               break;
> > +                       }
> > +               }
> > +
> >                 pr_debug("%s: req failed (CMD%u): %d, retrying...\n",
> >                          mmc_hostname(host), cmd->opcode, cmd->error);
> >                 cmd->retries--;
> > --
> > 1.7.9.5
> >