Re: [PATCH] mmc: sdhci-of-esdhc: set timeout to max before tuning

[Michael Walle]

Am 2020-10-21 17:04, schrieb Ulf Hansson:
> On Fri, 16 Oct 2020 at 14:50, Michael Walle <michael@xxxxxxxx> wrote:
> > Am 2020-10-16 12:53, schrieb Ulf Hansson:
> > > On Fri, 16 Oct 2020 at 01:12, Michael Walle <michael@xxxxxxxx> wrote:
> > >>
> > >> On rare occations there is the following error:
> > >>
> > >>   mmc0: Tuning timeout, falling back to fixed sampling clock
> > >>
> > >> There are SD cards which takes a significant longer time to reply to
> > >> the
> > >> first CMD19 command. The eSDHC takes the data timeout value into
> > >> account
> > >> during the tuning period. The SDHCI core doesn't explicitly set this
> > >> timeout for the tuning procedure. Thus on the slow cards, there might
> > >> be
> > >> a spurious "Buffer Read Ready" interrupt, which in turn triggers a
> > >> wrong
> > >> sequence of events. In the end this will lead to an unsuccessful
> > >> tuning
> > >> procedure and to the above error.
> > >>
> > >> To workaround this, set the timeout to the maximum value (which is the
> > >> best we can do) and the SDHCI core will take care of the proper
> > >> timeout
> > >> handling.
> > >>
> > >> Signed-off-by: Michael Walle <michael@xxxxxxxx>
> > >
> > > Sound like this should be tagged for stable, right?
> >
> > Yes, but I was unsure about that. I didn't find a lot of Fixes: tags 
> > in
> > the history of this driver (eg. for errata etc.)
> >
> > I could repost a v2 with a fixes tag if you like.
>
> If this is regression and you can point to a specific commit it fixes,
> then please yes!

That would be commit ba49cbd0936e ("mmc: sdhci-of-esdhc: add tuning
support"). But as of today it isn't much left of that original code.
So I don't know if adding that fixes tag will help a lot. Correct me
if I'm wrong.

-michael