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

[Ville Syrjälä]

On Thu, Dec 03, 2015 at 10:08:05PM +0100, Takashi Iwai wrote:
> On Thu, 03 Dec 2015 21:33:29 +0100,
> Ville Syrjälä 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...
> 
> Great, I'll try them out now.  But these look like fixing only the
> cursor issue.  Would they cover also the missing glyphs I experienced?

No. That's either userland, or some object/context/etc. getting corrupted
I think. I've had something like that occasionally too after some number of
suspend cycles, and usually fbcon is dead at that point too (just get a
black screen on VT switch).

I think we had some bug with not properly pinning the fbdev buffer which
could explain things getting corrupted. Chris had a fix I think, but I'm
not sure if that went anywhere. Chris?

-- 
Ville Syrjälä
Intel OTC