drm/amd/display: Fix race condition in DPIA AUX transfer

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commit ead08b95fa upstream.

[Why]
This fix was intended for improving on coding style but in the process
uncovers a race condition, which explains why we are getting incorrect
length in DPIA AUX replies. Due to the call path of DPIA AUX going from
DC back to DM layer then again into DC and the added complexities on top
of current DC AUX implementation, a proper fix to rely on current dc_lock
to address the race condition is difficult without a major overhual
on how DPIA AUX is implemented.

[How]
- Add a mutex dpia_aux_lock to protect DPIA AUX transfers
- Remove DMUB_ASYNC_TO_SYNC_ACCESS_* codes and rely solely on
  aux_return_code_type for error reporting and handling
- Separate SET_CONFIG from DPIA AUX transfer because they have quiet
  different processing logic
- Remove unnecessary type casting to and from void * type

Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: "Limonciello, Mario" <mario.limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Stylon Wang 2022-11-10 21:53:01 +08:00 • committed by Greg Kroah-Hartman

parent 4da108082a

commit 075e2099c3

3 changed files with 89 additions and 85 deletions

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151

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

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17

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

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10

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c

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