From: Wayne Lin Wayne.Lin@amd.com
[ Upstream commit 453b0016a054df0f442fda8a145b97a33816cab9 ]
[Why] Once mst topology is constructed, later on new connected monitors are reported to source by CSN message. Within CSN, there is no carried info of DPCD_REV comparing to LINK_ADDRESS reply. As the result, we might leave some ports connected to DP but without DPCD revision number which will affect us determining the capability of the DP Rx.
[How] Send out remote DPCD read when the port's dpcd_rev is 0x0 in detect_ctx(). Firstly, read out the value from DPCD 0x2200. If the return value is 0x0, it's likely the DP1.2 DP Rx then we reques revision from DPCD 0x0 again.
Reviewed-by: Hersen Wu hersenwu@amd.com Acked-by: Hamza Mahfooz hamza.mahfooz@amd.com Signed-off-by: Wayne Lin Wayne.Lin@amd.com Tested-by: Daniel Wheeler daniel.wheeler@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- .../display/amdgpu_dm/amdgpu_dm_mst_types.c | 38 ++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c index 652cf108b3c2..424f4cfc0e04 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c @@ -335,12 +335,48 @@ dm_dp_mst_detect(struct drm_connector *connector, { struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector); struct amdgpu_dm_connector *master = aconnector->mst_port; + struct drm_dp_mst_port *port = aconnector->port; + int connection_status;
if (drm_connector_is_unregistered(connector)) return connector_status_disconnected;
- return drm_dp_mst_detect_port(connector, ctx, &master->mst_mgr, + connection_status = drm_dp_mst_detect_port(connector, ctx, &master->mst_mgr, aconnector->port); + + if (port->pdt != DP_PEER_DEVICE_NONE && !port->dpcd_rev) { + uint8_t dpcd_rev; + int ret; + + ret = drm_dp_dpcd_readb(&port->aux, DP_DP13_DPCD_REV, &dpcd_rev); + + if (ret == 1) { + port->dpcd_rev = dpcd_rev; + + /* Could be DP1.2 DP Rx case*/ + if (!dpcd_rev) { + ret = drm_dp_dpcd_readb(&port->aux, DP_DPCD_REV, &dpcd_rev); + + if (ret == 1) + port->dpcd_rev = dpcd_rev; + } + + if (!dpcd_rev) + DRM_DEBUG_KMS("Can't decide DPCD revision number!"); + } + + /* + * Could be legacy sink, logical port etc on DP1.2. + * Will get Nack under these cases when issue remote + * DPCD read. + */ + if (ret != 1) + DRM_DEBUG_KMS("Can't access DPCD"); + } else if (port->pdt == DP_PEER_DEVICE_NONE) { + port->dpcd_rev = 0; + } + + return connection_status; }
static int dm_dp_mst_atomic_check(struct drm_connector *connector,