X-Git-Url: https://repo.jachan.dev/linux.git/blobdiff_plain/449dc8c97089a6e09fb2dac4d92b1b7ac0eb7c1e..f28e32d3906e:/drivers/gpu/drm/drm_dp_mst_topology.c

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 09b32289497e..61755c26fac0 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3486,6 +3486,28 @@ static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8  dp_link_count)
 	return dp_link_bw * dp_link_count / 2;
 }
 
+/**
+ * drm_dp_read_mst_cap() - check whether or not a sink supports MST
+ * @aux: The DP AUX channel to use
+ * @dpcd: A cached copy of the DPCD capabilities for this sink
+ *
+ * Returns: %True if the sink supports MST, %false otherwise
+ */
+bool drm_dp_read_mst_cap(struct drm_dp_aux *aux,
+			 const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 mstm_cap;
+
+	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
+		return false;
+
+	if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
+		return false;
+
+	return mstm_cap & DP_MST_CAP;
+}
+EXPORT_SYMBOL(drm_dp_read_mst_cap);
+
 /**
  * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
  * @mgr: manager to set state for
@@ -4308,11 +4330,11 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
 {
 	int ret;
 
-	port = drm_dp_mst_topology_get_port_validated(mgr, port);
-	if (!port)
+	if (slots < 0)
 		return false;
 
-	if (slots < 0)
+	port = drm_dp_mst_topology_get_port_validated(mgr, port);
+	if (!port)
 		return false;
 
 	if (port->vcpi.vcpi > 0) {
@@ -4328,6 +4350,7 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
 	if (ret) {
 		DRM_DEBUG_KMS("failed to init vcpi slots=%d max=63 ret=%d\n",
 			      DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
+		drm_dp_mst_topology_put_port(port);
 		goto out;
 	}
 	DRM_DEBUG_KMS("initing vcpi for pbn=%d slots=%d\n",