drm/amd/display: Link train only when link is DP and backend is enabled

[Why]
In certain cases we do link training when we don't have a backend.

[How]
In dc_link_set_preferred_link_settings(), store preferred link settings
first and then verify that the link is DP and the link stream's backend is
enabled.  If either is false, then we will not do any link retraining.

Signed-off-by: Samson Tam <[email protected]>
Reviewed-by: Aric Cyr <[email protected]>
Acked-by: Anthony Koo <[email protected]>
Acked-by: Bhawanpreet Lakha <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 260a01ebd888..699e1ee75035 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -524,6 +524,14 @@ void dc_link_set_preferred_link_settings(struct dc *dc,
 	struct dc_stream_state *link_stream;
 	struct dc_link_settings store_settings = *link_setting;
 
+	link->preferred_link_setting = store_settings;
+
+	/* Retrain with preferred link settings only relevant for
+	 * DP signal type
+	 */
+	if (!dc_is_dp_signal(link->connector_signal))
+		return;
+
 	for (i = 0; i < MAX_PIPES; i++) {
 		pipe = &dc->current_state->res_ctx.pipe_ctx[i];
 		if (pipe->stream && pipe->stream->link) {
@@ -538,7 +546,10 @@ void dc_link_set_preferred_link_settings(struct dc *dc,
 
 	link_stream = link->dc->current_state->res_ctx.pipe_ctx[i].stream;
 
-	link->preferred_link_setting = store_settings;
+	/* Cannot retrain link if backend is off */
+	if (link_stream->dpms_off)
+		return;
+
 	if (link_stream)
 		decide_link_settings(link_stream, &store_settings);