[Intel-gfx] [PATCH 3/9] drm/display/dp_mst: Add drm_atomic_get_old_mst_topology_state()

[Imre Deak <imre.deak@intel.com>]

Add a function to get the old MST topology state, required by a
follow-up i915 patch.

While at it clarify the code comment of
drm_atomic_get_new_mst_topology_state().

Cc: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org # 6.1
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 29 +++++++++++++++++--
 include/drm/display/drm_dp_mst_helper.h       |  3 ++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index ebf6e31e156e0..81cc0c3b1e000 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -5362,18 +5362,43 @@ struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_a
 }
 EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
 
+/**
+ * drm_atomic_get_old_mst_topology_state: get old MST topology state in atomic state, if any
+ * @state: global atomic state
+ * @mgr: MST topology manager, also the private object in this case
+ *
+ * This function wraps drm_atomic_get_old_private_obj_state() passing in the MST atomic
+ * state vtable so that the private object state returned is that of a MST
+ * topology object.
+ *
+ * Returns:
+ *
+ * The old MST topology state, or NULL if there's no topology state for this MST mgr
+ * in the global atomic state
+ */
+struct drm_dp_mst_topology_state *
+drm_atomic_get_old_mst_topology_state(struct drm_atomic_state *state,
+				      struct drm_dp_mst_topology_mgr *mgr)
+{
+	struct drm_private_state *priv_state =
+		drm_atomic_get_old_private_obj_state(state, &mgr->base);
+
+	return priv_state ? to_dp_mst_topology_state(priv_state) : NULL;
+}
+EXPORT_SYMBOL(drm_atomic_get_old_mst_topology_state);
+
 /**
  * drm_atomic_get_new_mst_topology_state: get new MST topology state in atomic state, if any
  * @state: global atomic state
  * @mgr: MST topology manager, also the private object in this case
  *
- * This function wraps drm_atomic_get_priv_obj_state() passing in the MST atomic
+ * This function wraps drm_atomic_get_new_private_obj_state() passing in the MST atomic
  * state vtable so that the private object state returned is that of a MST
  * topology object.
  *
  * Returns:
  *
- * The MST topology state, or NULL if there's no topology state for this MST mgr
+ * The new MST topology state, or NULL if there's no topology state for this MST mgr
  * in the global atomic state
  */
 struct drm_dp_mst_topology_state *
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index f5eb9aa152b14..32c764fb9cb56 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -868,6 +868,9 @@ struct drm_dp_mst_topology_state *
 drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
 				  struct drm_dp_mst_topology_mgr *mgr);
 struct drm_dp_mst_topology_state *
+drm_atomic_get_old_mst_topology_state(struct drm_atomic_state *state,
+				      struct drm_dp_mst_topology_mgr *mgr);
+struct drm_dp_mst_topology_state *
 drm_atomic_get_new_mst_topology_state(struct drm_atomic_state *state,
 				      struct drm_dp_mst_topology_mgr *mgr);
 struct drm_dp_mst_atomic_payload *
-- 
2.37.1