releases/5.0.20/drm-amd-display-link-train-only-when-link-is-dp-and-.patch

From 7dd97c2c3be165e99398b2148acc5e4a210e298e Mon Sep 17 00:00:00 2001
From: Samson Tam <Samson.Tam@amd.com>
Date: Mon, 4 Mar 2019 16:21:06 -0500
Subject: drm/amd/display: Link train only when link is DP and backend is
 enabled

[ Upstream commit 66acd4418d7de131ef3831e52a8af3d2480e5b15 ]

[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 <Samson.Tam@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/dc/core/dc.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 5af2ea1f201d3..68529acba015f 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->sink
@@ -539,7 +547,10 @@ 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);
 
-- 
2.20.1