[Mesa-dev] [PATCH 2/2] winsys/amdgpu: disable CE preamble until the kernel is fixed

[Marek Olšák]

I'm dropping the patch. It makes UE4 Elemental hang. We have a bigger
CE issue than I thought. It could be a Mesa issue too.

Marek

On Fri, May 27, 2016 at 12:12 PM, Marek Olšák <maraeo at gmail.com> wrote:
> On Fri, May 27, 2016 at 11:12 AM, Christian König
> <deathsimple at vodafone.de> wrote:
>> Am 27.05.2016 um 00:19 schrieb Marek Olšák:
>>>
>>> On Fri, May 27, 2016 at 12:13 AM, Alex Deucher <alexdeucher at gmail.com>
>>> wrote:
>>>>
>>>> On Thu, May 26, 2016 at 5:51 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>>>
>>>>> From: Marek Olšák <marek.olsak at amd.com>
>>>>>
>>>>> SDMA submission somehow interacts with the skipping CE preamble logic.
>>>>> This is a workaround for current kernels which have the bug.
>>>>>
>>>>> Sadly, I can't see what's wrong with the kernel driver. The CE preamble
>>>>> handling there looks good to me.
>>>>>
>>>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=95545
>>>>
>>>> What exactly is going wrong?  Is the kernel not scheduling the
>>>> preamble or is the ordering wrong or something else?
>>>
>>> There are VM faults for addresses that are too far away from memory
>>> allocated by the process.
>>>
>>> It looks like the contents of CE RAM come from a different process,
>>> which suggests that the CE preamble IB was skipped.
>>>
>>> Disabling the CE preamble IB means that the preamble packets are added
>>> to the main CE IB instead, which makes the problem go away.
>>
>>
>> Just a guess, but does commit 9f8fb5a2b339ba83493991ca8f1173a939a696d3 in
>> Alex drm-next-4.7 tree helps with the problem?
>>
>> commit 9f8fb5a2b339ba83493991ca8f1173a939a696d3
>> Author: Christian König <christian.koenig at amd.com>
>> Date:   Fri May 6 14:52:57 2016 +0200
>>
>>     drm/amdgpu: move preamble IB handling into common code
>>
>>     This fixes the handling which was completely broken when you
>>     ad more than one preamble IB.
>
> I'm using amd-staging-4.5, which has that. Apparently it doesn't help.
>
> Marek