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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