drm/amdgpu/sdma3: Work around POLL_REGMEM / FENCE hang

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SDMA can randomly hang on Polaris 10. Hard to reproduce,
but has been occurring sporadically in the Mesa CI
on the RADV Polaris 10 job even when Mesa isn't using
the SDMA engine.

When Mesa actually uses the SDMA on Polaris, the hang
becomes more frequent and the reproduction rate goes up
significantly in the CI system.

We don't know why the hangs occur, but it seems
that inserting a single NOP packet before each
POLL_REGMEM and FENCE packet works around it.
At the moment it's unclear which GPUs are affected,
so let's apply this to SDMA 3.x for now.

Note that this issue is not documented or acknowledged by AMD.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit c343a27ed90823d08de125f7c447d96d056b75d9)
Cc: stable@vger.kernel.org

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This commit is contained in:

Timur Kristóf 2026-10-07 00:02:52 +02:00 • committed by Alex Deucher

parent 3c44cbcec5

commit 752480ad62

1 changed files with 21 additions and 4 deletions

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drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c

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