Add drm_dp_mst_port_downstream_of_parent() required by the i915
driver in a follow-up patch to resolve a BW overallocation of MST
streams going through a given MST port.
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
---
drivers/gpu/drm/display/drm_dp_mst_topology.c | 52 +++++++++++++++++++
include/drm/display/drm_dp_mst_helper.h | 3 ++
2 files changed, 55 insertions(+)
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index db97aa76575c1..22a901493d24c 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -5136,6 +5136,58 @@ static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
return false;
}
+static bool
+drm_dp_mst_port_downstream_of_parent_locked(struct drm_dp_mst_topology_mgr *mgr,
+ struct drm_dp_mst_port *port,
+ struct drm_dp_mst_port *parent)
+{
+ if (!mgr->mst_primary)
+ return false;
+
+ port = drm_dp_mst_topology_get_port_validated_locked(mgr->mst_primary,
+ port);
+ if (!port)
+ return false;
+
+ if (!parent)
+ return true;
+
+ parent = drm_dp_mst_topology_get_port_validated_locked(mgr->mst_primary,
+ parent);
+ if (!parent)
+ return false;
+
+ if (!parent->mstb)
+ return false;
+
+ return drm_dp_mst_port_downstream_of_branch(port, parent->mstb);
+}
+
+/**
+ * drm_dp_mst_port_downstream_of_parent - check if a port is downstream of a parent port
+ * @mgr: MST topology manager
+ * @port: the port being looked up
+ * @parent: the parent port
+ *
+ * The function returns %true if @port is downstream of @parent. If @parent is
+ * %NULL - denoting the root port - the function returns %true if @port is in
+ * @mgr's topology.
+ */
+bool
+drm_dp_mst_port_downstream_of_parent(struct drm_dp_mst_topology_mgr *mgr,
+ struct drm_dp_mst_port *port,
+ struct drm_dp_mst_port *parent)
+{
+ bool ret;
+
+ mutex_lock(&mgr->lock);
+ ret = drm_dp_mst_port_downstream_of_parent_locked(mgr, port, parent);
+ mutex_unlock(&mgr->lock);
+
+ return ret;
+}
+EXPORT_SYMBOL(drm_dp_mst_port_downstream_of_parent);
+
static int
drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
struct drm_dp_mst_topology_state *state);
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index 5de0c3d28794b..aecce52cae167 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -892,6 +892,9 @@ drm_atomic_get_new_mst_topology_state(struct drm_atomic_state *state,
struct drm_dp_mst_atomic_payload *
drm_atomic_get_mst_payload_state(struct drm_dp_mst_topology_state *state,
struct drm_dp_mst_port *port);
+bool drm_dp_mst_port_downstream_of_parent(struct drm_dp_mst_topology_mgr *mgr,
+ struct drm_dp_mst_port *port,
+ struct drm_dp_mst_port *parent);
int __must_check
drm_dp_atomic_find_time_slots(struct drm_atomic_state *state,
struct drm_dp_mst_topology_mgr *mgr,
--
2.37.2
