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

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

[Public]

> >
> > IIRC this is the bug you want linked in the commit message:
> >
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitla
> b.freedesktop.org%2Fdrm%2Famd%2F-
> %2Fissues%2F1671&data=04%7C01%7CMario.Limonciello%40amd.com
> %7C5559a4f23f46426add1808da0773b4ac%7C3dd8961fe4884e608e11a82d994
> e183d%7C0%7C0%7C637830490785879396%7CUnknown%7CTWFpbGZsb3d8
> eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3
> D%7C3000&sdata=P%2FBcLeN9rnjGam4kh68ZQUBAPIDM4G%2Bk1ukb5
> k%2BRFVg%3D&reserved=0
> 
> 
> Ah, thanks. Most of the people on this bug seem like their problem was
> that they didn't have the nvidia-wmi-ec-backlight driver, which also
> didn't exist at the time the bug was filed. There is one person with a
> newer comment reporting behavior that sounds like what this patch works
> around, and it is the same person who initially reported the issue to me. :)
> 
> 

Thanks for looking at those.

> > But these two look possible to be the same root cause:
> >
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitla
> b.freedesktop.org%2Fdrm%2Famd%2F-
> %2Fissues%2F1791&data=04%7C01%7CMario.Limonciello%40amd.com
> %7C5559a4f23f46426add1808da0773b4ac%7C3dd8961fe4884e608e11a82d994
> e183d%7C0%7C0%7C637830490785879396%7CUnknown%7CTWFpbGZsb3d8
> eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3
> D%7C3000&sdata=Bv3lJJOG7BZxlvizh0L4gmHgakzjlJkl7TqGh9HTho4%3D
> &reserved=0
> 
> 
> This one sounds like it might be a different issue, since it was
> apparently working at some point with a kernel that didn't have the EC
> backlight driver, and then not working on a newer kernel that also
> didn't have the EC backlight driver. That is, of course, assuming
> vanilla kernels: it is certainly possible that the EC backlight driver
> was backported.
> 
> >
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitla
> b.freedesktop.org%2Fdrm%2Famd%2F-
> %2Fissues%2F1794&data=04%7C01%7CMario.Limonciello%40amd.com
> %7C5559a4f23f46426add1808da0773b4ac%7C3dd8961fe4884e608e11a82d994
> e183d%7C0%7C0%7C637830490785879396%7CUnknown%7CTWFpbGZsb3d8
> eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3
> D%7C3000&sdata=JfUhLPRIMVLypLXoAxKhpSw7WIN4M%2BS4Y48MQ
> %2BzXdbk%3D&reserved=0
> 
> 
> This sounds like it could possibly be a simple case of not having the EC
> backlight driver. Notably, the backlight device exposed by the amdgpu
> driver never works, in contrast to the system these workarounds are
> targeting, where the amdgpu driver's backlight device initially works,
> but then stops working after the first suspend/resume cycle (and the EC
> backlight driver doesn't work initially, but then starts working after
> suspend/resume).

I guess when we see backlight issues on these A+N designs the checks should be:
1) Are they supposed to be using the nvidia-wmi-ec-backlight driver?
2) Is their kernel new enough to have it?
3) Do they have the config enabled?

Do you have a script or could you perhaps include some documentation we can
point people to check "1" so we don't always have to go tear apart ACPI tables
and make guesses?

I guess it's something like grab _WDG and then parse it to see if there is an entry.

> 
> 
> >
> > 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.
> >
> 
> v1 already has the quirks plumbed up to module parameters (those module
> parameters just don't have corresponding sysfs entries). In any case, I
> only see one report between those bugs that sounds like the issue these
> WARs are meant to address, and since it's from the same reporter, it
> sounds like we won't need to be adding any additional quirks table
> entries right away.
> 
> 
> >>
> >>> 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.
> >>
> >>