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SubjectRe: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7 merge window
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On 23.06.2016 13:25, James Bottomley wrote:
> On Tue, 2016-06-21 at 17:00 -0400, James Bottomley wrote:
>> On Tue, 2016-06-21 at 18:44 +0300, Ville Syrjälä wrote:
>>> On Tue, Jun 21, 2016 at 09:53:15AM -0400, James Bottomley wrote:
>>>> On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote:
>>>>> Cc: Ville
>>>>>
>>>>> On Mon, 20 Jun 2016, James Bottomley <
>>>>> James.Bottomley@HansenPartnership.com> wrote:
>>>>>> OK, my candidate bad commit is this one:
>>>>>>
>>>>>> commit a05628195a0d9f3173dd9aa76f482aef692e46ee
>>>>>> Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>>>> Date: Mon Apr 11 10:23:51 2016 +0300
>>>>>>
>>>>>> drm/i915: Get panel_type from OpRegion panel details
>>>>>>
>>>>>> After being more careful about waiting to identify flicker,
>>>>>> this one seems to be the one the bisect finds. I'm now
>>>>>> running v4.7-rc3 with this one reverted and am currently
>>>>>> seeing no flicker problems. It is, however, early days
>>>>>> because the flicker can hide for long periods, so I 'll wait
>>>>>> until Monday evening and a few reboots before declaring
>>>>>> victory.
>>>>>
>>>>> If that turns out to be the bad commit, it doesn't really
>>>>> surprise me, and that in itself is depressing.
>>>>
>>>> As far as I can tell, after running for a day with this reverted,
>>>> this is the problem. The flicker hasn't appeared with it
>>>> reverted. It's pretty noticeable with this commit included.
>>>
>>> Hmm. The only difference I can see is low vs. normal vswing. Panel
>>> 0 has low, panel 2 has normal. So either the VBT or opregion is
>>> telling utter lies, or there's some other bug in our low vswing
>>> support.
>>>
>>> To confirm it's really a vswing issue, you should be able to run
>>> with i915.edp_vswing=2 without flickers on the broken kernel.
>>
>> Preliminary boot indicates no flicker with the bad commit included
>> and this option, but I'll have to run for quite a bit longer to
>> verify, since it can sometimes be elusive.
>
> Two days of runtime seems to confirm this is the problem (still no
> flicker issues).

This issue is listed in my regression reports for 4.7 and I wonder what
the status is. It seems nothing happened for more then a week now, which
is a bad sign as 4.7 final seems only a week or two away.

CU, Thorsten

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