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

[Takashi Iwai]

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.

There were no obvious errors or GPU hang in both kernel and X logs
when these happened.  Also, the issue was gone once when I restarted
X even without reboot.  (But then it seems re-triggering the bug more
shortly.)

I've had this a few times and never had this before 4.4-rc1.  It's
intermittent and very hard to reproduce.  Possibly triggered by a high
memory usage or such.

Also today I experienced a similar mouse pointer vanish on an IVY
desktop.  Though, I cannot judge whether this is the same cause.

Since I'm using openSUSE Tumbleweed that is a rolling release, I can't
blame only kernel.  But, my gut feeling tells it's probably a kernel
regression, something like a cache issue.  Alas, it's impossible to
bisect due to the difficulty of bug reproduction.

Can anyone give some hint for debugging once when this problem happens
again?


thanks,

Takashi