drm/amdgpu: Add debugfs to drop UALink protocol messages

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Introduce a debugfs-controlled bitmap, amdgpu_ualink_drop_msg_bitmap,
where each bit corresponds to a value from
enum AMDGPU_UALINK_PROTOCOL_MESSAGES (e.g. NPA-REQ, NPA-RSP, NPA-FAIL,
NPA-REVOKE, NPA-RELEASE).

When a bit is set, the next incoming message of that type is dropped
in amdgpu_ualink_process_irq() and the bit is atomically cleared via
test_and_clear_bit(), so subsequent incoming messages are processed
normally. This allows exercising the UALink connection reset and
recovery paths (NPA-RSP timeout on the importer, retransmit/teardown
on the exporter, etc.) by injecting a single packet loss from
userspace, e.g.:

    # drop one NPA-REQ
    echo 0x08 > /sys/kernel/debug/dri/0/amdgpu_ualink_drop_msg_bitmap
    # drop one NPA-RSP
    echo 0x10 > /sys/kernel/debug/dri/0/amdgpu_ualink_drop_msg_bitmap

The bitmap lives in struct amdgpu_ualink_mgr and is exposed via
debugfs_create_ulong() next to the existing amdgpu_ualink_test entry.

Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

...

This commit is contained in:

Mukul Joshi 2026-06-03 22:24:45 -04:00 • committed by Alex Deucher

parent ec1087853e

commit 4bf8beb242

3 changed files with 43 additions and 0 deletions

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14

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

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13

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

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16

drivers/gpu/drm/amd/amdgpu/amdgpu_ualink.h

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