[PATCH 4.20 231/352] drm/amd/display: validate extended dongle caps

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 99b922f9ed6a6313c0d2247cde8aa1e4a0bd67e4 ]

[why]
Some dongle doesn't have a valid extended dongle caps,
but we still set the extended dongle caps to be valid.
This causes validation fails for all timing.

[how]
If no dp_hdmi_max_pixel_clk is provided,
don't use extended dongle caps.

Signed-off-by: Wenjing Liu <Wenjing.Liu@xxxxxxx>
Reviewed-by: Aric Cyr <Aric.Cyr@xxxxxxx>
Reviewed-by: Jun Lei <Jun.Lei@xxxxxxx>
Acked-by: Abdoulaye Berthe <Abdoulaye.Berthe@xxxxxxx>
Acked-by: Leo Li <sunpeng.li@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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 d91df5ef0cb3..d33a5ebe990b 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
@@ -2240,7 +2240,8 @@ static void get_active_converter_info(
 					translate_dpcd_max_bpc(
 						hdmi_color_caps.bits.MAX_BITS_PER_COLOR_COMPONENT);
 
-				link->dpcd_caps.dongle_caps.extendedCapValid = true;
+				if (link->dpcd_caps.dongle_caps.dp_hdmi_max_pixel_clk != 0)
+					link->dpcd_caps.dongle_caps.extendedCapValid = true;
 			}
 
 			break;
-- 
2.19.1