From 4716a7c50c5c66d6ddc42401e1e0ba13b492e105 Mon Sep 17 00:00:00 2001
From: Bing Guo <bing.guo@amd.com>
Date: Mon, 4 Jan 2021 14:09:41 -0500
Subject: [PATCH] drm/amd/display: Change function decide_dp_link_settings to avoid infinite looping
Git-commit: 4716a7c50c5c66d6ddc42401e1e0ba13b492e105
Patch-mainline: v5.11-rc5
References: git-fixes

Why: 
Function decide_dp_link_settings() loops infinitely when required bandwidth
can't be supported.

How: 
Check the required bandwidth against verified_link_cap before trying to
find a link setting for it.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Bing Guo <bing.guo@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <anson.jacob@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 3 +++
 1 file changed, 3 insertions(+)

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 1bd1a0935290..28b4b084199c 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
@@ -2399,6 +2399,9 @@ static bool decide_dp_link_settings(struct dc_link *link, struct dc_link_setting
 			initial_link_setting;
 	uint32_t link_bw;
 
+	if (req_bw > dc_link_bandwidth_kbps(link, &link->verified_link_cap))
+		return false;
+
 	/* search for the minimum link setting that:
 	 * 1. is supported according to the link training result
 	 * 2. could support the b/w requested by the timing
-- 
2.26.2