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

[Maarten Lankhorst]

Op 09-04-18 om 21:48 schreef Rodrigo Vivi:
> On Wed, Mar 28, 2018 at 06:20:26PM +0200, Maarten Lankhorst wrote:
>> 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.
> What about a error message change on fbc_status to reflect this temporary state?
> Just to avoid later confusion on expectation.
Done, if an underrun is cleared, the reason will be set to 'FIFO underrun cleared'.
> But the approach and code look sane for me, so anyways:
>
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
Thanks for reviewing, pushed. :)