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

From: Alexandru Dinu <alex.dinu07@gmail.com>
To: "platform-driver-x86@vger.kernel.org" 
	<platform-driver-x86@vger.kernel.org>
Subject: RE: [PATCH] nvidia-wmi-ec-backlight: Add workarounds for confused firmware
Date: Wed, 16 Mar 2022 22:13:14 +0200	[thread overview]
Message-ID: <CAJOTRr6bhe7pHPAH04BYpwjY9k2bu5ufK93vo6FsWO8U+02zXg@mail.gmail.com> (raw)

Hi,

> I'll send out a v2 shortly: Alex, can you
please retest when I do to make sure there aren't any regressions? None
of these suggestions affect the core flow of how either of the
workarounds work, so I'm not expecting any that wouldn't also reproduce
on my EC backlight system that doesn't have either of these problems,
but I can send you the updated version off-list first if you prefer.

It's ok either way. You can send me an updated version off-list.

> 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.

Yes, thanks -- I followed this issue first:
https://gitlab.freedesktop.org/drm/amd/-/issues/1671.

> 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.

That's a good tip. The laptop I tested this on (Lenovo Legion S7
15ACH6) originally shipped with:

UEFI: LENOVO v: HACN27WW date: 08/02/2021

There is an update to version HACN31WW -- see
https://support.lenovo.com/ro/en/downloads/ds550201-bios-update-for-windows-10-64-bit-legion-s7-15ach6
I updated, however, the issue was not addressed, which seems to be
expected given the rather short /changelog:
HACN31WW
BIOS Notification    :
1. Fixed
 1) N/A.
2. Add
  1) Add BOE0A1C support with Cookie and DR Key
3. Modified
  1) Modify MinShortTerm & MinLongTerm PowerLimit value
EC Notification      :
1. Fixed
  1) None.
2. Add
   1) None.
3. Modified
  1)None.

> 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.

I posted a link to this mailing list to
https://gitlab.freedesktop.org/drm/amd/-/issues/1671, so people can be
aware and try to test.

Regards,
Alex