Radeon R700 multi-ring bug

[Marek Olšák]

Disabling DPM makes no difference.

Marek

On Sat, Apr 19, 2014 at 5:19 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Sat, Apr 19, 2014 at 11:07 AM, Marek Olšák <maraeo at gmail.com> wrote:
>> This test always reproduces the issue for me:
>>
>> piglit/bin/arb_vertex_buffer_object-vbo-subdata-many drawarrays -fbo -auto
>>
>> There are rejected IBs and it hangs sometimes.
>>
>> It started to fail with this commit:
>> http://cgit.freedesktop.org/mesa/mesa/commit/?id=6d434252e239bc872549e59c64eb3d0e5dab0655
>>
>> which is probably unrelated to the issue, but it makes the graphics IB
>> a little bit bigger.
>>
>> Also, I think R700 is generally in a bad shape. I haven't been able to
>> run piglit with concurrency and without hangs, and I have already
>> disabled async DMA, geometry shaders, and pipelined buffer uploads.
>
> See if disabling dpm helps.
>
> Alex
>
>>
>> Marek
>>
>> On Sat, Apr 19, 2014 at 11:54 AM, Christian König
>> <deathsimple at vodafone.de> wrote:
>>> Hi Marek,
>>>
>>> I've noticed this before as well, and I agree that it looks like a memory
>>> corruption. Not sure if the async DMA on the GPU or the CPU is overwriting
>>> something because of a race condition or something like this.
>>>
>>> Anyway, can you come up with a simple test case to reproduce the issue? For
>>> me it occurred only randomly while working on UVD support for R7xx. If you
>>> have something more reliable I could dig into it with my RV710.
>>>
>>> Christian.
>>>
>>> Am 19.04.2014 01:48, schrieb Marek Olšák:
>>>>
>>>> Hi,
>>>>
>>>> If you submit a lot of graphics and DMA IBs interleaved, the graphics
>>>> CS checker sometimes fails with this message:
>>>>
>>>> [ 3846.435661] Forbidden register 0x0014 in cs at 9
>>>> [ 3846.435664] [drm:radeon_cs_ib_chunk] *ERROR* Invalid command stream !
>>>>
>>>> This error is only used for type-0 packets, but we don't use these
>>>> packets on R700 at all. Somehow, the graphics CS checker received
>>>> either the DMA IB or random garbage. My guess is there is memory
>>>> corruption happening during IB uploading and/or IB checking in the
>>>> kernel. Also, if you are unlucky, the GPU hangs instead.
>>>>
>>>> The CS thread offloading was disabled in Mesa, so the user space was
>>>> single-threaded.
>>>>
>>>> There are 2 ways to fix this:
>>>> - disable async DMA in Mesa
>>>> - call usleep(1) after the RADEON_CS ioctl returns
>>>>
>>>> This is just a heads-up. In the worst case, we can disable async DMA
>>>> for R700 in Mesa.
>>>>
>>>> Marek
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>>>
>>>
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