Contrary to the smu_cmn_send_smc_msg_with_param documentation, two
cases exist where messages are silently dropped with no error returned
to the caller. These cases occur in unusual situations where either:
1. the message target is a virtual GPU, or
2. a PCI recovery is underway and the HW is not yet in sync with the SW
For more details see
commit 4ea5081c82c4 ("drm/amd/powerplay: enable SMC message filter")
commit bf36b52e781d ("drm/amdgpu: Avoid accessing HW when suspending SW state")
(v2)
Reworked with suggestions from Luben & Paul
Signed-off-by: Darren Powell <darren.powell@xxxxxxx>
---
drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
index b8d0c70ff668..8008ae5508e6 100644
--- a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
@@ -356,9 +356,11 @@ int smu_cmn_wait_for_response(struct smu_context *smu)
* completion of the command, and return back a value from the SMU in
* @read_arg pointer.
*
- * Return 0 on success, -errno on error, if we weren't able to send
- * the message or if the message completed with some kind of
- * error. See __smu_cmn_reg2errno() for details of the -errno.
+ * Return 0 on success, -errno when a problem is encountered sending
+ * message or receiving reply. If there is a PCI bus recovery or
+ * the destination is a virtual GPU, the message is simply dropped and
+ * success is also returned.
+ * See __smu_cmn_reg2errno() for details of the -errno.
*
* If we weren't able to send the message to the SMU, we also print
* the error to the standard log.
base-commit: 4585c45a6a66cb17cc97f4370457503746e540b7
--
2.35.1
