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drm/amd/display: Detect dpcd_rev when hotplug mst monitor

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[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>
This commit is contained in:
Wayne Lin 2022-04-20 10:32:15 +08:00 committed by Alex Deucher
parent 84de5c2e92
commit 453b0016a0
1 changed files with 37 additions and 1 deletions
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38
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
View File

@ -344,12 +344,48 @@ 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,