Re: [PATCH] driver: pca953x: avoid error message when resuming

[Linus Walleij]

On Mon, Jun 20, 2022 at 6:03 PM Andy Shevchenko
<andy.shevchenko@xxxxxxxxx> wrote:
> On Mon, Jun 20, 2022 at 4:18 PM Pierluigi Passaro
> <pierluigi.p@xxxxxxxxxxxxx> wrote:

> > > > Avoids the error messages "pca953x 1-0020: failed reading register"
> > > > when resuming from suspend using gpio-key attached to pca9534.
> > > Thanks for your report and fix. My comments below.
> > > First of all, how many of them do you get and why is it a problem?
> >
> > The number of occurrences depends on the time required to I2C bus to fully wake-up.
> > It's not a real problem, but the message may lead to think about a real I2C problem.
>
> Wolfram, do we have any mechanisms that guarantees that I2C traffic is
> not going on a semi-woken up host controller?
>
> Writing this, I'm in doubt this patch is a fix we want. Wouldn't it
> just hide the real issue with some resume ordering?

That sounds like a bug in the pm routines in the I2C driver. Why is it
returning from [runtime_]resume() if it is not properly resumed?

Yours,
Linus Walleij