From: Harmanprit Tatla harmanprit.tatla@amd.com

[ 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@amd.com Reviewed-by: Aric Cyr aric.cyr@amd.com Acked-by: Anthony Koo Anthony.Koo@amd.com Acked-by: Leo Li sunpeng.li@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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: