[Intel-gfx] [PATCH 3/3] drm/i915: remove the vblank_wait hack from HSW+

[Paulo Zanoni]

2013/12/19 Daniel Vetter <daniel at ffwll.ch>:
> On Thu, Dec 19, 2013 at 10:12 PM, Paulo Zanoni <przanoni at gmail.com> wrote:
>> From: Paulo Zanoni <paulo.r.zanoni at intel.com>
>>
>> When I forked haswell_crtc_enable I copied all the code from
>> ironlake_crtc_enable. The last piece of the function contains a big
>> comment with a call to intel_wait_for_vblank. After this fork, we
>> rearranged the Haswell code so that it enables the planes as the very
>> last step of the modeset sequence, so we're sure that we call
>> intel_enable_primary_plane after the pipe is really running, so the
>> vblank waiting functions work as expected. I really believe this is
>> what fixes the problem described by the big comment, so let's give it
>> a try and get rid of that intel_wait_for_vblank, saving around 16ms
>> per modeset (and init/resume). We can always revert if needed :)
>>
>> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
>
> If kms_flip doesn't start failing you're good. Iirc I've added some
> flip vs. modeset and flip vs. dpms tests specifically for this.

It already fails on plain -nightly, even without any of my patches on it :(

I'm testing on a HSW ULT with eDP-only. It's hard to see all the tests
that fail due to the huge output print by the test, but I can see here
that at least flip-vs-modeset-vs-hang, flip-vs-panning-vs-hang and
flip-vs-dpms-off-vs-modeset fail, and also my machine is frozen while
running single-buffer-flip-vs-dpms-off-vs-modeset... So I can't even
run kms_flip with my patches and then without them to compare if I
introduce a new regression

I also don't see a bug report about this specific Haswell failure, so
I wonder for how long this is broken :(

I also feel I have to complain about the fact that kms_flip runs for
about 45 minutes (before it hangs my machine, so total time may be
even more). I just wanted to do a quick "check if I broke the test
which exercises the bug", but then it takes forever to finish... Can
you please point at specific subtests you were talking about?

> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch



-- 
Paulo Zanoni