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

[Chris Wilson]

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.
-Chris