diff options
Diffstat (limited to 'include/drm/drm_dp_mst_helper.h')
| -rw-r--r-- | include/drm/drm_dp_mst_helper.h | 32 |
1 files changed, 28 insertions, 4 deletions
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h index 7d80c38ee00e..bccb5514e0ef 100644 --- a/include/drm/drm_dp_mst_helper.h +++ b/include/drm/drm_dp_mst_helper.h @@ -55,8 +55,6 @@ struct drm_dp_vcpi { * @num_sdp_stream_sinks: Number of stream sinks * @available_pbn: Available bandwidth for this port. * @next: link to next port on this branch device - * @mstb: branch device on this port, protected by - * &drm_dp_mst_topology_mgr.lock * @aux: i2c aux transport to talk to device connected to this port, protected * by &drm_dp_mst_topology_mgr.lock * @parent: branch device parent of this port @@ -92,7 +90,17 @@ struct drm_dp_mst_port { u8 num_sdp_stream_sinks; uint16_t available_pbn; struct list_head next; - struct drm_dp_mst_branch *mstb; /* pointer to an mstb if this port has one */ + /** + * @mstb: the branch device connected to this port, if there is one. + * This should be considered protected for reading by + * &drm_dp_mst_topology_mgr.lock. There are two exceptions to this: + * &drm_dp_mst_topology_mgr.up_req_work and + * &drm_dp_mst_topology_mgr.work, which do not grab + * &drm_dp_mst_topology_mgr.lock during reads but are the only + * updaters of this list and are protected from writing concurrently + * by &drm_dp_mst_topology_mgr.probe_lock. + */ + struct drm_dp_mst_branch *mstb; struct drm_dp_aux aux; /* i2c bus for this port? */ struct drm_dp_mst_branch *parent; @@ -118,7 +126,6 @@ struct drm_dp_mst_port { * @lct: Link count total to talk to this branch device. * @num_ports: number of ports on the branch. * @msg_slots: one bit per transmitted msg slot. - * @ports: linked list of ports on this branch. * @port_parent: pointer to the port parent, NULL if toplevel. * @mgr: topology manager for this branch device. * @tx_slots: transmission slots for this device. @@ -156,6 +163,16 @@ struct drm_dp_mst_branch { int num_ports; int msg_slots; + /** + * @ports: the list of ports on this branch device. This should be + * considered protected for reading by &drm_dp_mst_topology_mgr.lock. + * There are two exceptions to this: + * &drm_dp_mst_topology_mgr.up_req_work and + * &drm_dp_mst_topology_mgr.work, which do not grab + * &drm_dp_mst_topology_mgr.lock during reads but are the only + * updaters of this list and are protected from updating the list + * concurrently by @drm_dp_mst_topology_mgr.probe_lock + */ struct list_head ports; /* list of tx ops queue for this port */ @@ -503,6 +520,13 @@ struct drm_dp_mst_topology_mgr { struct mutex lock; /** + * @probe_lock: Prevents @work and @up_req_work, the only writers of + * &drm_dp_mst_port.mstb and &drm_dp_mst_branch.ports, from racing + * while they update the topology. + */ + struct mutex probe_lock; + + /** * @mst_state: If this manager is enabled for an MST capable port. False * if no MST sink/branch devices is connected. */ |