[Intel-gfx] [PATCH] drm/i915/fbc: disable FBC on FIFO underruns

[Stefan Richter]

On Jun 10 Paulo Zanoni wrote:
> Since my test machines don't produce FIFO underrun errors, I tested this by
> creating a debugfs file that just calls intel_fbc_handle_fifo_underrun(). I'd
> appreciate some Tested-by tags, if possible.

Since May 8 I have been using 4.6.0-rc6 patched with
drm-intel-nightly_2016y-05m-06d-14h-29m-58s (from what I understand,
something close to what is now in mainline), and fbc disabled on the
kernel commandline.  I have not rebooted since May 8.

For that kernel, i915.enable_fbc=0 is both required and sufficient to
prevent freezes at random points in time (as reported).  The
drm-intel-nightly_2016y-05m-06d-14h-29m-58s patch on the other hand has the
effect that there are never any FIFO underruns logged anymore.

If there are no FIFO underruns reported in dmesg, your underrun
detection routine would never hit, would it?

If you nevertheless think it's worth trying, should I test it on top of
4.7-rc3 or on current drm-intel-nightly?
-- 
Stefan Richter
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