drm/amd/display: Respect aux return values

[Why]
The new aux implementation was not up to spec. This caused us to fail DP
compliance as well as introduced serious delays during system resume.

[How]
Make dce_aux_transfer_raw return the operation result

Make dce_aux_transfer_with_retries delay with udelay instead
of msleep, and only on invalid reply.  Also fail on the second
invalid reply, third timeout, or first of any other error

Convert return values to drm error codes in amdgpu_dm

As the two aux transfer functions are now noticeably
different, change the names to better reflect their
functionality and document.

There was one last call to dc_link_aux_transfer that
should have retries, fix that

Signed-off-by: David Francis <David.Francis@amd.com>
Signed-off-by: Thomas Lim <Thomas.Lim@amd.com>
Reviewed-by: David Francis <David.Francis@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Acked-by: Eric Yang <eric.yang2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 19 insertions, 3 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
index b7ee63cd8dc7..f02092a0dc76 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
@@ -573,12 +573,28 @@ bool dal_ddc_service_query_ddc_data(
 	return ret;
 }
 
-int dc_link_aux_transfer(struct ddc_service *ddc,
-		struct aux_payload *payload)
+/* dc_link_aux_transfer_raw() - Attempt to transfer
+ * the given aux payload.  This function does not perform
+ * retries or handle error states.  The reply is returned
+ * in the payload->reply and the result through
+ * *operation_result.  Returns the number of bytes transferred,
+ * or -1 on a failure.
+ */
+int dc_link_aux_transfer_raw(struct ddc_service *ddc,
+		struct aux_payload *payload,
+		enum aux_channel_operation_result *operation_result)
 {
-	return dce_aux_transfer(ddc, payload);
+	return dce_aux_transfer_raw(ddc, payload, operation_result);
 }
 
+/* dc_link_aux_transfer_with_retries() - Attempt to submit an
+ * aux payload, retrying on timeouts, defers, and busy states
+ * as outlined in the DP spec.  Returns true if the request
+ * was successful.
+ *
+ * Unless you want to implement your own retry semantics, this
+ * is probably the one you want.
+ */
 bool dc_link_aux_transfer_with_retries(struct ddc_service *ddc,
 		struct aux_payload *payload)
 {