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

[Chris Wilson]

Quoting Jani Nikula (2018-03-06 10:55:02)
> On Tue, 06 Mar 2018, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > Quoting Lofstedt, Marta (2018-03-06 10:39:04)
> >> 
> >> 
> >> > -----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. 
> >
> > It may just be that we see the same error. Some errors like underruns
> > permanently disable FBC (afaik).
> 
> Could we add a way to manually force enable FBC in that case? debugfs?

Or a (CRTC?) property, userspace sets it to desired, kernel updates to off/on?
(Now that is a very old dream.)
-Chris