drm/amd/display: Change function decide_dp_link_settings to avoid infinite looping

[ Upstream commit 4716a7c50c5c66d6ddc42401e1e0ba13b492e105 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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 9846488..004e2b3 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -2375,6 +2375,9 @@ 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