[igt-dev] [PATCH i-g-t] igt/kms_frontbuffer_tracking: Skip tests if FBC was disabled

[Lofstedt, Marta]

> -----Original Message-----
> From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
> Sent: Tuesday, March 6, 2018 11:32 AM
> To: Lofstedt, Marta <marta.lofstedt at intel.com>; igt-
> dev at lists.freedesktop.org
> Subject: Re: [igt-dev] [PATCH i-g-t] igt/kms_frontbuffer_tracking: Skip tests if
> FBC was disabled
> 
> Quoting Marta Lofstedt (2018-03-06 09:24:57)
> > If FBC has been disabled in the system due to previous malfuction, we
> > would save time on CI if we bail out early.
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105359
> > Signed-off-by: Marta Lofstedt <marta.lofstedt at intel.com>
> 
> Hmm, FBC starts inactive on a system, so we would need to ensure that we
> enabled FBC and did a proper modeset first and wait for FBC to be enabled
> first.

On the SKL NUCi5 system I have been running this on, the FBC disabled sysfs, isn't re-set after a modeset. Maybe this is a driver error that should not be hidden by me suggesting to skip the tests. 

On the other hand, the kms_frontbuffer_tracking test should give different results if FBC is disabled compared to timeout in the fbc_wait_until_enabled() which up until some time ago was the most common way to fail this test. 

> 
> Otherwise, it seems very reasonable that in this test we assume that FBC
> works before we begin. We should have other tests that check that FBC
> works under various different configurations, here we are checking that the
> invalidate/flush do their jobs.
> -Chris