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

Ville Syrjälä ville.syrjala at linux.intel.com
Fri Dec 4 01:40:59 PST 2015

On Fri, Dec 04, 2015 at 10:49:48AM +0200, Jani Nikula wrote:
> 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?

The potential for it has definitely been there for a long time.

Ville Syrjälä
Intel OTC

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