[PATCH 5.2 064/144] drm/amd/display: No audio endpoint for Dell MST display

[Greg Kroah-Hartman]

[ Upstream commit 5b25e5f1a97284020abee7348427f89abdb674e8 ]

[Why]
There are certain MST displays (i.e. Dell P2715Q)
that although have the MST feature set to off may still
report it is a branch device and a non-zero
value for downstream port present.
This can lead to us incorrectly classifying a
dp dongle connection as being active and
disabling the audio endpoint for the display.

[How]
Modified the placement and
condition used to assign
the is_branch_dev bit.

Signed-off-by: Harmanprit Tatla <harmanprit.tatla@xxxxxxx>
Reviewed-by: Aric Cyr <aric.cyr@xxxxxxx>
Acked-by: Anthony Koo <Anthony.Koo@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 | 9 ++++++++-
 1 file changed, 8 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 253311864cdd5..966aa3b754c5b 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
@@ -2218,11 +2218,18 @@ static void get_active_converter_info(
 		link->dpcd_caps.dongle_type = DISPLAY_DONGLE_NONE;
 		ddc_service_set_dongle_type(link->ddc,
 				link->dpcd_caps.dongle_type);
+		link->dpcd_caps.is_branch_dev = false;
 		return;
 	}
 
 	/* DPCD 0x5 bit 0 = 1, it indicate it's branch device */
-	link->dpcd_caps.is_branch_dev = ds_port.fields.PORT_PRESENT;
+	if (ds_port.fields.PORT_TYPE == DOWNSTREAM_DP) {
+		link->dpcd_caps.is_branch_dev = false;
+	}
+
+	else {
+		link->dpcd_caps.is_branch_dev = ds_port.fields.PORT_PRESENT;
+	}
 
 	switch (ds_port.fields.PORT_TYPE) {
 	case DOWNSTREAM_VGA:
-- 
2.20.1