drm/display/dp_mst: Handle old/new payload states in drm_dp_remove_payload()

Atm, drm_dp_remove_payload() uses the same payload state to both get the
vc_start_slot required for the payload removal DPCD message and to
deduct time_slots from vc_start_slot of all payloads after the one being
removed.

The above isn't always correct, as vc_start_slot must be the up-to-date
version contained in the new payload state, but time_slots must be the
one used when the payload was previously added, contained in the old
payload state. The new payload's time_slots can change vs. the old one
if the current atomic commit changes the corresponding mode.

This patch let's drivers pass the old and new payload states to
drm_dp_remove_payload(), but keeps these the same for now in all drivers
not to change the behavior. A follow-up i915 patch will pass in that
driver the correct old and new states to the function.

Cc: Lyude Paul <[e-mail]>
Cc: Ville Syrjälä <[e-mail]>
Cc: Ben Skeggs <[e-mail]>
Cc: Karol Herbst <[e-mail]>
Cc: Harry Wentland <[e-mail]>
Cc: Alex Deucher <[e-mail]>
Cc: Wayne Lin <[e-mail]>
Cc: [e-mail] # 6.1
Cc: [e-mail]
Reviewed-by: Ville Syrjälä <[e-mail]>
Reviewed-by: Lyude Paul <[e-mail]>
Acked-by: Lyude Paul <[e-mail]>
Acked-by: Daniel Vetter <[e-mail]>
Acked-by: Wayne Lin <[e-mail]>
Acked-by: Jani Nikula <[e-mail]>
Signed-off-by: Imre Deak <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c

···
 	if (enable)
 		drm_dp_add_payload_part1(mst_mgr, mst_state, payload);
 	else
-		drm_dp_remove_payload(mst_mgr, mst_state, payload);
+		drm_dp_remove_payload(mst_mgr, mst_state, payload, payload);
 
 	/* mst_mgr->->payloads are VC payload notify MST branch using DPCD or
 	 * AUX message. The sequence is slot 1-63 allocated sequence for each

drivers/gpu/drm/display/drm_dp_mst_topology.c

···
  * drm_dp_remove_payload() - Remove an MST payload
  * @mgr: Manager to use.
  * @mst_state: The MST atomic state
- * @payload: The payload to write
+ * @old_payload: The payload with its old state
+ * @new_payload: The payload to write
  *
  * Removes a payload from an MST topology if it was successfully assigned a start slot. Also updates
  * the starting time slots of all other payloads which would have been shifted towards the start of
···
  */
 void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
 			   struct drm_dp_mst_topology_state *mst_state,
-			   struct drm_dp_mst_atomic_payload *payload)
+			   const struct drm_dp_mst_atomic_payload *old_payload,
+			   struct drm_dp_mst_atomic_payload *new_payload)
 {
 	struct drm_dp_mst_atomic_payload *pos;
 	bool send_remove = false;
 
 	/* We failed to make the payload, so nothing to do */
-	if (payload->vc_start_slot == -1)
+	if (new_payload->vc_start_slot == -1)
 		return;
 
 	mutex_lock(&mgr->lock);
-	send_remove = drm_dp_mst_port_downstream_of_branch(payload->port, mgr->mst_primary);
+	send_remove = drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr->mst_primary);
 	mutex_unlock(&mgr->lock);
 
 	if (send_remove)
-		drm_dp_destroy_payload_step1(mgr, mst_state, payload);
+		drm_dp_destroy_payload_step1(mgr, mst_state, new_payload);
 	else
 		drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in topology, not sending remove\n",
-			    payload->vcpi);
+			    new_payload->vcpi);
 
 	list_for_each_entry(pos, &mst_state->payloads, next) {
-		if (pos != payload && pos->vc_start_slot > payload->vc_start_slot)
-			pos->vc_start_slot -= payload->time_slots;
+		if (pos != new_payload && pos->vc_start_slot > new_payload->vc_start_slot)
+			pos->vc_start_slot -= old_payload->time_slots;
 	}
-	payload->vc_start_slot = -1;
+	new_payload->vc_start_slot = -1;
 
 	mgr->payload_count--;
-	mgr->next_start_slot -= payload->time_slots;
+	mgr->next_start_slot -= old_payload->time_slots;
 
-	if (payload->delete)
-		drm_dp_mst_put_port_malloc(payload->port);
+	if (new_payload->delete)
+		drm_dp_mst_put_port_malloc(new_payload->port);
 }
 EXPORT_SYMBOL(drm_dp_remove_payload);
 

drivers/gpu/drm/i915/display/intel_dp_mst.c

···
 		to_intel_connector(old_conn_state->connector);
 	struct drm_dp_mst_topology_state *mst_state =
 		drm_atomic_get_mst_topology_state(&state->base, &intel_dp->mst_mgr);
+	struct drm_dp_mst_atomic_payload *payload =
+		drm_atomic_get_mst_payload_state(mst_state, connector->port);
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 
 	drm_dbg_kms(&i915->drm, "active links %d\n",
···
 	intel_hdcp_disable(intel_mst->connector);
 
 	drm_dp_remove_payload(&intel_dp->mst_mgr, mst_state,
-			      drm_atomic_get_mst_payload_state(mst_state, connector->port));
+			      payload, payload);
 
 	intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
 }

drivers/gpu/drm/nouveau/dispnv50/disp.c

···
 
 	// TODO: Figure out if we want to do a better job of handling VCPI allocation failures here?
 	if (msto->disabled) {
-		drm_dp_remove_payload(mgr, mst_state, payload);
+		drm_dp_remove_payload(mgr, mst_state, payload, payload);
 
 		nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head->base.index, 0, 0, 0, 0);
 	} else {

include/drm/display/drm_dp_mst_helper.h

···
 			     struct drm_dp_mst_atomic_payload *payload);
 void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
 			   struct drm_dp_mst_topology_state *mst_state,
-			   struct drm_dp_mst_atomic_payload *payload);
+			   const struct drm_dp_mst_atomic_payload *old_payload,
+			   struct drm_dp_mst_atomic_payload *new_payload);
 
 int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);