Re: [PATCH] tty: max310x: work around regmap->regcache data corruption

[Andy Shevchenko]

On Fri, Dec 1, 2023 at 6:21 PM Mark Brown <broonie@xxxxxxxxxx> wrote:
> On Fri, Dec 01, 2023 at 03:51:51PM +0100, Jan Kundrát wrote:
>
> > The TL;DR summary is that the regmap_noinc_write spills over the data
> > that are correctly written to the HW also to the following registers in
> > the regcache. As a result, regcache then contains user-controlled
> > garbage which will be used later for bit updates on unrelated registers.
>
> > I was investigating a regression that happened somewhere between 5.12.4
> > (plus 14 of our patches) and v6.5.9 (plus 7 of our patches). Our
>
> Can you reproduce this with current kernels?  That's not even an up to
> date v6.5 - we're up to v6.5.13 now from the looks of things including
> one upstream fix that looks potentially relevant.

Indeed, the 984a4afdc87a ("regmap: prevent noinc writes from
clobbering cache") seems quite relevant.

-- 
With Best Regards,
Andy Shevchenko