[Intel-gfx] [PATCH] drm/i915: Restore the wait for idle engine after flushing interrupts

[Chris Wilson]

Quoting Mika Kuoppala (2017-11-10 12:19:42)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > So it appears that commit 5427f207852d ("drm/i915: Bump wait-times for
> > the final CS interrupt before parking") was a little over optimistic in
> > its belief that it had successfully waited for all residual activity on
> > the engines before parking. Numerous sightings in CI since then of
> >
> > <7>[   52.542886] [IGT] core_auth: executing
> > <3>[   52.561013] [drm:intel_engines_park [i915]] *ERROR* vcs0 is not idle before parking
> > <7>[   52.561215] intel_engines_park vcs0
> > <7>[   52.561229] intel_engines_park  current seqno 98, last 98, hangcheck 0 [-247449 ms], inflight 0
> > <7>[   52.561238] intel_engines_park  Reset count: 0
> > <7>[   52.561266] intel_engines_park  Requests:
> > <7>[   52.561363] intel_engines_park  RING_START: 0x00000000 [0x00000000]
> > <7>[   52.561377] intel_engines_park  RING_HEAD:  0x00000000 [0x00000000]
> > <7>[   52.561390] intel_engines_park  RING_TAIL:  0x00000000 [0x00000000]
> > <7>[   52.561406] intel_engines_park  RING_CTL:   0x00000000
> > <7>[   52.561422] intel_engines_park  RING_MODE:  0x00000200 [idle]
> > <7>[   52.561442] intel_engines_park  ACTHD:  0x00000000_00000000
> > <7>[   52.561459] intel_engines_park  BBADDR: 0x00000000_00000000
> > <7>[   52.561474] intel_engines_park  Execlist status: 0x00000301 00000000
> > <7>[   52.561489] intel_engines_park  Execlist CSB read 5 [5 cached], write 5 [5 from hws], interrupt posted? no
> > <7>[   52.561500] intel_engines_park          ELSP[0] idle
> > <7>[   52.561510] intel_engines_park          ELSP[1] idle
> > <7>[   52.561519] intel_engines_park          HW active? 0x0
> > <7>[   52.561608] intel_engines_park Idle? yes
> > <7>[   52.561617] intel_engines_park
> >
> > on Braswell, which indicates that the engine just needs that little bit
> > longer after flushing the tasklet to settle. So give it a few more
> > milliseconds before declaring an emergency and applying the emergency
> > brake.
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103479
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> 
> Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

Pushed to keep CI quiet. If we still get an error here, it will be
interesting (and hopefully the engine state provide a clue). The only
problem is without the constant poking, we're likely to forget the race
here.

Thanks,
-Chris