[Intel-gfx] [PATCH] drm/i915: Add debugfs file to clear FIFO underruns.

[Maarten Lankhorst]

Op 28-03-18 om 12:21 schreef Jani Nikula:
> On Wed, 28 Mar 2018, Maarten Lankhorst <maarten.lankhorst at linux.intel.com> wrote:
>> Adding a i915_fifo_underrun_reset debugfs file will make it possible
>> for IGT tests to clear FIFO underrun fallout at the start of each
>> subtest, and make re-enable FBC so tests always have maximum exposure
>> to features used by IGT. FIFO underruns and FBC bugs will no longer
>> hide when an earlier subtests disables both.
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105685
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105681
> FWIW, ack on the idea, didn't look at the implementation.
Well I had a NV12 test that produced FIFO underruns, did some quick testing against the i915_fifo_underrun_reset file and manually writing it does reset FIFO underruns.
Immediately after i915_fbc_status still reads "FBC disabled: underrun detected", but this is cleared by the next atomic commit. So I think it works, and can be used for igt in the way I wrote it.

~Maarten