From: Jimmy Kizito <Jimmy.Kizito@amd.com>
Date: Wed, 25 Aug 2021 23:12:08 +0000 (-0400)
Subject: drm/amd/display: Fix link training fallback logic
X-Git-Tag: howlett/maple/20220722_2~1941^2~13^2~21
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=4de0bfe67bc98fb2a1115bc58ef3b9bc21717629;p=users%2Fjedix%2Flinux-maple.git

drm/amd/display: Fix link training fallback logic

[Why]
Link training should fail if stream bandwidth exceeds link bandwidth.

[How]
Correct fallback logic and use named variables to make intention clear.

Reviewed-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 7ea505109340..e3f102425fee 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -2462,12 +2462,16 @@ bool perform_link_training_with_retries(
 			if (type == dc_connection_none)
 				break;
 		} else if (do_fallback) {
+			uint32_t req_bw;
+			uint32_t link_bw;
+
 			decide_fallback_link_setting(*link_setting, &current_setting, status);
 			/* Fail link training if reduced link bandwidth no longer meets
 			 * stream requirements.
 			 */
-			if (dc_bandwidth_in_kbps_from_timing(&stream->timing) <
-					dc_link_bandwidth_kbps(link, &current_setting))
+			req_bw = dc_bandwidth_in_kbps_from_timing(&stream->timing);
+			link_bw = dc_link_bandwidth_kbps(link, &current_setting);
+			if (req_bw > link_bw)
 				break;
 		}