[Intel-gfx] Possible i915 regression with 4.4-rc

[Jani Nikula]

On Thu, 03 Dec 2015, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> On Thu, Dec 03, 2015 at 09:00:55PM +0100, Takashi Iwai wrote:
>> Hi,
>> 
>> I've experienced a few graphics issues recently, and I tend to believe
>> that it has happened since 4.4-rc.  Namely, after some long time usage
>> on my HSW laptop (two or three days), the mouse cursor vanished
>> suddenly.  It kept pointing but just became invisible.  Also, after
>> some S3 cycles, some glyphs on a console or on Firefox became
>> invisible, too.  The windows and graphics were shown well, and X core
>> fonts were still shown properly, too.  Switching to VT1 and back
>> didn't change the situation.
>
> I think I have a fix for this *very* annoying problem. I'v been cursing
> on irc for weeks about it, until I finally got off my arse and debugged
> it.
>
> I pushed out my my cursor branch:
> git://github.com/vsyrjala/linux.git disappearing_cursor_fix
>
> It has lots of other junk too, but it should be just there two that fix it:
> 59f65fa270fb ("drm/i915: Kill intel_crtc->cursor_bo")
> 25651a198d17 ("drm/i915: Drop the broken curcor base==0 special casing")
>
> Unfortunatleey I've managed to keep myself busy on other stuff, so didn't
> send them out yet. Maybe tomorrow...

So I've hit this too, albeit very rarely, on a Haswell running Debian
stable with the stock v3.16 kernel. Haven't seen it on any other
machine. It's really too rare to even debug or verify a fix. Is it
possible we just happened to make an old bug occur more frequently now?

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Technology Center