[PATCH 0/1][SRU][Jammy] dmesg flooded with errors: amdgpu: DP AUX transfer fail:4

[You-Sheng Yang]

BugLink: https://bugs.launchpad.net/bugs/2115238

[ Impact ]

v6.15-rc6 commit 65924ec69b292 ("drm/amd/display: Fix wrong handling for
AUX_DEFER case") added a `drm_info()` call to notify a failed
transaction, and that may flood kernel dmesg buffer. This was then fixed
by another v6.15-rc7 commit d33724ffb743d ("drm/amd/display: Avoid
flooding unnecessary info messages").

The former was also backported to v6.14.7, v6.12.29, v6.6.91, v6.1.139,
v5.15.183.

The later to v6.14.8, v6.12.30, v6.6.92, v6.1.140.

- linux-6.14/plucky version 6.14.0-24.24 has v6.14.6, not yet affected,
- linux-6.11/oracular master-next has v6.6.88, v6.12.25, not yet
  affected,
- linux-6.8/noble version 6.8.0-64.67 has v6.6.77, v6.12.14, not yet
  affected,
- linux-5.15/jammy version 5.15.0-144.157 has v5.15.184, affected and
  the solution is not (yet?) backported to stable tree.

- linux-oem-6.14/noble version 6.14.0-1005.5 has the former through
  bug 2110095,
- linux-oem-6.11/noble version 6.11.0-1024.24 has the former through
  bug 2110095

[ Test Plan ]

The fix reduce log level from `drm_info()` to `drm_dbg_dp()`, so it
shall stop to appear by default.

Following messages flood kernel dmesg buffer after some GPU testing
operations if reproduced:
```
$ sudo dmesg|grep 'DP AUX transfer'
...
amdgpu 0000:c4:00.0: amdgpu: [drm] amdgpu: DP AUX transfer fail:4
$ sudo dmesg|grep 'DP AUX transfer' | wc -l
896
```

[ Where problems could occur ]

Lower debug message level only.

[ Other Info ]

Nominate for oem-6.11, oem-6.14 and linux/jammy so far. For N/O/P, they
should have both the cause and the fix at the same time if there is a
next stable backport for them.

Wayne Lin (1):
  drm/amd/display: Avoid flooding unnecessary info messages

 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

-- 
2.48.1