[PATCH v4 4/5] drm/dp-mst: Fill branch->num_ports

[David Francis]

This field on drm_dp_mst_branch was never filled

Initialize it to zero when the list of ports is created.
When a port is added to the list, increment num_ports,
and when a port is removed from the list, decrement num_ports.

v2: remember to decrement on port removal

Signed-off-by: David Francis <David.Francis at amd.com>
Reviewed-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 50a044718439..af4b5cec7c84 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -919,6 +919,7 @@ static struct drm_dp_mst_branch *drm_dp_add_mst_branch_device(u8 lct, u8 *rad)
 	INIT_LIST_HEAD(&mstb->ports);
 	kref_init(&mstb->topology_kref);
 	kref_init(&mstb->malloc_kref);
+	mstb->num_ports = 0;
 	return mstb;
 }
 
@@ -1669,6 +1670,7 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
 		mutex_lock(&mstb->mgr->lock);
 		drm_dp_mst_topology_get_port(port);
 		list_add(&port->next, &mstb->ports);
+		mstb->num_ports++;
 		mutex_unlock(&mstb->mgr->lock);
 	}
 
@@ -1703,6 +1705,7 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
 			/* remove it from the port list */
 			mutex_lock(&mstb->mgr->lock);
 			list_del(&port->next);
+			mstb->num_ports--;
 			mutex_unlock(&mstb->mgr->lock);
 			/* drop port list reference */
 			drm_dp_mst_topology_put_port(port);
-- 
2.17.1