[Intel-gfx] i915 issues with 4.6

[Pierre-Louis Bossart]

On 5/18/16 2:08 AM, Ville Syrjälä wrote:
> On Tue, May 17, 2016 at 07:09:58PM -0500, Pierre-Louis Bossart wrote:
>>
>>
>> On 05/17/2016 01:16 PM, Ville Syrjälä wrote:
>>> On Tue, May 17, 2016 at 01:00:13PM -0500, Pierre-Louis Bossart wrote:
>>>> Hi,
>>>> I was porting the HDMI audio patch to 4.6 as a service to several folks
>>>> who need them before we finally upstream the reworked code, and I notice
>>>> that the UI would freeze within 2s to 5mn, with all sorts of GPU hangs
>>>> and issues reported in dmesg and /sys/calls/drm/card0/error
>>>> Things work fine with the latest drm-intel-nightly branch from last night
>>>> Known issue or should I file a bug?
>>> One GPU hang generally looks like any other from the symptom POV.
>>> Without the error state it's pretty much impossible to speculate.
>>> Just filing a new bug is usually the best policy.
>>>
>>> If it's indeed a kernel regression a bisect would also be helpful.
>>> Or in this case perhaps a reverse bisect since you say nightly is
>>> fine, so we might want to know what fixed it.
>>
>> bug filed at https://bugs.freedesktop.org/show_bug.cgi?id=95467
>>
>> V4.5 works fine
>> v4.6 is broken in less than 20s when moving windows around (can still
>> get to virtual console)
>> drm-intel-nightly works fine
>>
>> git bisect says this commit fixes the issue:
>>
>> commit a5e485a95c9c4cdd93b4c6dc53eee3bd1e50de11
>> Author: Ville Syrjälä <ville.syrjala at linux.intel.com <mailto:ville.syrjala at linux.intel.com>>
>> Date:   Wed Apr 13 21:19:51 2016 +0300
>>
>>      drm/i915: Clear VLV_IER around irq processing
>
> Argh. So somehow the broken commit [1] got into 4.6. We'll need to get
> it reverted.
>
> [1] 9dbaab56ac09 ("drm/i915: Exit cherryview_irq_handler() after one pass")

git revert 9dbaab56ac09 works fine on my Ara X5 Plus.