[Intel-gfx] [PATCH i-g-t] tests/kms_pipe_crc_basic: Reset GPU before running subtests

[Mika Kahola]

On Tue, 2017-06-06 at 14:23 +0100, Chris Wilson wrote:
> Quoting Mika Kahola (2017-06-06 13:33:14)
> > 
> > On Tue, 2017-06-06 at 15:27 +0300, Ville Syrjälä wrote:
> > > 
> > > On Tue, Jun 06, 2017 at 03:20:46PM +0300, Mika Kahola wrote:
> > > > 
> > > > 
> > > > It has been noticed by our CI BAT testing that in some 1%-3%
> > > > probability
> > > > kms_pipe_crc_basic subtest read-crc-pipe-x-frame-sequence fails
> > > > when
> > > > comparing gathered CRC frames. However, running
> > > > kms_pipe_crc_basic
> > > > subtests alone i.e. outside BAT I was unable to replicate the
> > > > issue.
> > > > 
> > > > The patch proposes a GPU reset before running the subtests.
> > > > This
> > > > way we
> > > > can ensure that GPU register settings are reinitialized if they
> > > > have been
> > > > altered by the tests executed earlier in BAT.
> > > What does GPU reset have to do with display CRCs?
> > It's unclear but when you do it I was unable to replicate this in
> > couple hundred BAT runs. Maybe the error probability just hits
> > below 1%
> > mark with this.
> So trace through what side-effect the reset may have and find the bug
> in
> the kernel.
I'm a bit puzzled with this bug. By running the test alone doesn't
trigger the issue but this occurs only when running fast-feedback.
testlist. Maybe tearing down the previous tests cause some sort of
instability which is then triggered when running this test? Any hints
or pointers where to look at?


> -Chris
-- 
Mika Kahola - Intel OTC