[PATCH v1] i2c: imx: Retry transfer on transient failure

[Francesco Dolcini]

+ oleksandr.suvorov at foundries.io

Hello all,

On Tue, Jul 12, 2022 at 12:05:04PM +0200, Francesco Dolcini wrote:
> On Tue, Jul 12, 2022 at 11:05:14AM +0200, Uwe Kleine-König wrote:
> > In which situations does this help? Please mention these in the
> > commit log.
> I'll do

I did some investigation on this, unfortunately we have this change
laying around since 1 year, it was written by Oleksandr, and in the
meantime he moved to a new company. I added him to this email thread, so
he can comment in case he remembers more.

We introduced this change while working on OV5640 camera sensor on an
apalis-imx6q evaluation board, without this change we had some sporadic
i2c communication issues. Unfortunately I do not have any better
details.

To me looks like having some (3? 5?) retry as a default is somehow
more reasonable than to never retry, not sure if this should be
implemented as a default for all the i2c adapters. From what I was able
to see that would not be a trivial change (the retry parameter is coming
from the i2c_imx driver, there is no obvious way to have a default in
the i2c core).

Would it work for you to keep the change as it is (just getting rid
of the useless define) and add a little bit more blurb to the commit
message to include the various comments collected so far?

Francesco