[Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7 merge window

[Daniel Vetter]

On Thu, Jun 16, 2016 at 11:15 PM, James Bottomley
<James.Bottomley at hansenpartnership.com> wrote:
> On Mon, 2016-06-13 at 13:14 +0300, Jani Nikula wrote:
>> On Tue, 31 May 2016, James Bottomley <
>> James.Bottomley at HansenPartnership.com> wrote:
>> > On Tue, 2016-05-31 at 10:51 +0300, Jani Nikula wrote:
>> > > On Mon, 30 May 2016, James Bottomley <
>> > > James.Bottomley at HansenPartnership.com> wrote:
>> > > > I've tested a pristine 4.6.0 system, so it's definitely
>> > > > something
>> > > > that
>> > > > went in during the merge window.  The flicker isn't continuous,
>> > > > it's
>> > > > periodic, with an interval of something like 2-5 seconds.  It
>> > > > looks
>> > > > like an old analogue TV going out of sync and then resyncing.
>> > > >  I've
>> > > > attached the dmesg and X.org log below just in case they can
>> > > > help.
>> > > >  I
>> > > > might be able to bisect this next week, but, unfortunately,
>> > > > this is
>> > > > my
>> > > > current laptop and I'm travelling this week.
>> > >
>> > > Please try i915.enable_psr=0 module parameter.
>> >
>> > Makes no discernable difference.  Current parameter settings are:
>>
>> Sorry for the silence. Would you mind trying out drm-intel-nightly
>> branch of [1]?
>>
>> BR,
>> Jani.
>>
>> [1] http://cgit.freedesktop.org/drm-intel
>
> No, flicker is still there (and in fact seems worse) with the tree with
> this commit at the top:
>
> commit 3eb202ecc3668583f9ff4338211dbab47d755d1c
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Thu Jun 16 14:38:54 2016 +0200
>
>     drm-intel-nightly: 2016y-06m-16d-12h-38m-37s UTC integration
> manifest

Strange indeed, I hoped the improved watermark code in -nightly would
help. I assume nothing in dmesg about underruns or something similar?
I guess we'll need the bisect on this one to make progress.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch