RE: [PATCH] nvidia-wmi-ec-backlight: Add workarounds for confused firmware

["Limonciello, Mario" <Mario.Limonciello@amd.com>]

[Public]

> On 3/16/22 10:29 AM, Limonciello, Mario wrote:
> > [Public]
> >
> > + Alex D
> >
> > Alex, just FYI this was something that came to an AMD bug tracker and
> wanted you to be aware there are W/A going into nvidia-wmi-ec-backlight
> for some firmware problems with the mux.
> > IIRC that was the original suspicion too on the bug reports.
> 
> 
> Is this on a public or private bug tracker? If this was observed on
> systems other than the one already added to these quirks, could you
> share the details of the systems so they can be added as well? (Or I
> suppose you may want to test to see if these WARs are effective on the
> affected systems as well; we can always expand the quirks table later.)

We (AMD folks) don't have the affected systems, we were just trying to help
users and things pointed at this driver, which seems to have yielded a good
investigation and conclusion!

IIRC this is the bug you want linked in the commit message:
https://gitlab.freedesktop.org/drm/amd/-/issues/1671

But these two look possible to be the same root cause:
https://gitlab.freedesktop.org/drm/amd/-/issues/1791
https://gitlab.freedesktop.org/drm/amd/-/issues/1794

If you end up introducing a module parameter to try to activate these quirks
it might be viable to ask the folks in those issues to try the v2 of your patch too
when you're ready with the module parameter.

> 
> 
> > Comments inline as well.
> >
> >> -----Original Message-----
> >> From: Daniel Dadap <ddadap@nvidia.com>
> >> Sent: Wednesday, March 16, 2022 10:11
> >> To: Barnabás Pőcze <pobrn@protonmail.com>
> >> Cc: platform-driver-x86@vger.kernel.org; Alexandru Dinu
> >> <alex.dinu07@gmail.com>; Hans de Goede <hdegoede@redhat.com>;
> >> markgross@kernel.org
> >> Subject: Re: [PATCH] nvidia-wmi-ec-backlight: Add workarounds for
> >> confused firmware
> >>
> 
> [ ... ]
> 
> 
> >>
> >> On 3/15/22 9:50 PM, Barnabás Pőcze wrote:
> >>>   [ ... ]
> >>> Lastly, is it expected that these bugs will be properly fixed?
> >>
> >> Possibly, but I wouldn't hold out hope for it for an issue at this scale
> >> on an already shipping system.
> > This question I'm assuming was aimed at narrowing the quirk to only
> > match certain FW versions or so.  If there is no certainty of when/if it
> > will be fixed I agree with current direction.
> > However I think it's still worth at least noting near the quirk in a comment
> > what firmware version it was identified.  If later there is confirmation that
> > a particular firmware version had fixed it the quirk can be adjusted to be
> > dropped.
> >
> 
> Thanks, Mario. Sure, I'll make sure the firmware version this was first
> observed in is noted.
> 
>