commit 15512021eb3975a8c2366e3883337e252bb0eee5 causes white spots in console screens

[Lisovskiy, Stanislav]

On Wed, Apr 13, 2022 at 08:12:20PM +0300, Jani Nikula wrote:
> On Wed, 13 Apr 2022, François Valenduc <francoisvalenduc at gmail.com> wrote:
> > Commit 15512021eb3975a8c2366e3883337e252bb0eee5 
> > (15512021eb3975a8c2366e3883337e252bb0eee5) causes a lof of white spots 
> > to appears on the right upper corner of all console screens (see 
> > https://drive.google.com/file/d/13GabEvOIKSAj5yox6ybAZEDu3Ixncw5Q/view). 
> > git-bisect shows that this is the offending commit and if I revert it, 
> > the problem goes away. The problem still occurs with kernel 5.18-rc2 and 
> > to all stable trees where it was applied.
> > Can somebody explains what happens ?
> >
> > The video card is the following: VGA compatible controller: Intel 
> > Corporation WhiskeyLake-U GT2 [UHD Graphics 620] (rev 02) (prog-if 00 
> > [VGA controller])
> >
> > Please tell me if you need more info.
> 
> That's commit 15512021eb39 ("drm/i915: Workaround broken BIOS DBUF
> configuration on TGL/RKL"), adding Cc's.
> 
> Please file a report at fdo gitlab [1] and attach dmesg etc. there.

That commit looks like it is just disabling all the planes, if wrong
dbuf/wm configuration is detected.
However it should do that only once during boot as I understand.

Are you sure that is exactly this commit which is causing this?
Does the issue appear always?

Ville Syrjälä, thoughts?

Stan

> 
> Thanks,
> Jani.
> 
> 
> [1] https://gitlab.freedesktop.org/drm/intel/wikis/How-to-file-i915-bugs
> 
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center