[Intel-gfx] [PATCH i-g-t] kms_rotation_crc: 90 degree flip test is not a stress test

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-08-03 14:09:59)
> 
> On 03/08/2017 13:53, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2017-08-03 13:42:50)
> >> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >>
> >> To the best of my recollection the page flipping test was added
> >> simply to start exercising page flips with 90/270 rotation.
> >>
> >> There is no need to do 60 flips which can take quite some time
> >> because we test each pipe and then each fb geometry. And
> >> calling this a stress test is also not matching the original
> >> idea of the test.
> >>
> >> So remove the stress from the name and reduce the number of
> >> flips to three only.
> > 
> > Considering this found a bug, do we have an explicit test that says a
> > rotated page flip takes no longer than a vblank (given the right
> > conditions, i.e subsequent flips)?
> 
> That was just me misremembering how the test work, wasn't a bug. Once I 
> looked at the code in more detail I realized the test does much more 
> flipping than it initially seemed. Num_pipes * 4 fb geometries * 2 
> framebuffers * 60 flips. In total around 8 seconds of flipping per pipe. 
> So the 25 second runtime is in line with 3 pipes at 60Hz plus some test 
> setup time.

Ah. But do we have a test that says we can hit vrefresh with rotated
pipes? I know we check the timings for the ordinary case, but from a
quick check of the likely suspects, I can't see such a test.

PS please add the explanation for why it took longer than expected into
the commit log.
-Chris