drm/dp_mst: Remove port validation in drm_dp_atomic_find_vcpi_slots()

Since we now have an easy way of refcounting drm_dp_mst_port structs and
safely accessing their contents, there isn't any good reason to keep
validating ports here. It doesn't prevent us from performing modesets on
branch devices that have been removed either, and we already disallow
enabling new displays on unregistered connectors in
update_connector_routing() in drm_atomic_check_modeset(). All it does is
cause us to have to make weird special exceptions in our atomic
modesetting code. So, get rid of it entirely.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: eceae14 ("drm/dp_mst: Start tracking per-port VCPI allocations")
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190202002023.29665-3-lyude@redhat.com

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -3117,10 +3117,6 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 	if (IS_ERR(topology_state))
 		return PTR_ERR(topology_state);
 
-	port = drm_dp_mst_topology_get_port_validated(mgr, port);
-	if (port == NULL)
-		return -EINVAL;
-
 	/* Find the current allocation for this port, if any */
 	list_for_each_entry(pos, &topology_state->vcpis, next) {
 		if (pos->port == port) {
@@ -3153,10 +3149,8 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 	/* Add the new allocation to the state */
 	if (!vcpi) {
 		vcpi = kzalloc(sizeof(*vcpi), GFP_KERNEL);
-		if (!vcpi) {
-			ret = -ENOMEM;
-			goto out;
-		}
+		if (!vcpi)
+			return -ENOMEM;
 
 		drm_dp_mst_get_port_malloc(port);
 		vcpi->port = port;
@@ -3165,8 +3159,6 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 	vcpi->vcpi = req_slots;
 
 	ret = req_slots;
-out:
-	drm_dp_mst_topology_put_port(port);
 	return ret;
 }
 EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);

drivers/gpu/drm/i915/intel_dp_mst.c

@@ -80,17 +80,12 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 	mst_pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock, bpp);
 	pipe_config->pbn = mst_pbn;
 
-	/* Zombie connectors can't have VCPI slots */
-	if (!drm_connector_is_unregistered(connector)) {
-		slots = drm_dp_atomic_find_vcpi_slots(state,
-						      &intel_dp->mst_mgr,
-						      port,
-						      mst_pbn);
-		if (slots < 0) {
-			DRM_DEBUG_KMS("failed finding vcpi slots:%d\n",
-				      slots);
-			return slots;
-		}
+	slots = drm_dp_atomic_find_vcpi_slots(state, &intel_dp->mst_mgr, port,
+					      mst_pbn);
+	if (slots < 0) {
+		DRM_DEBUG_KMS("failed finding vcpi slots:%d\n",
+			      slots);
+		return slots;
 	}
 
 	intel_link_compute_m_n(bpp, lane_count,

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

@@ -771,8 +771,7 @@ nv50_msto_atomic_check(struct drm_encoder *encoder,
 	mstc->pbn = drm_dp_calc_pbn_mode(crtc_state->adjusted_mode.clock,
 					 bpp);
 
-	if (drm_atomic_crtc_needs_modeset(crtc_state) &&
-	    !drm_connector_is_unregistered(connector)) {
+	if (drm_atomic_crtc_needs_modeset(crtc_state)) {
 		slots = drm_dp_atomic_find_vcpi_slots(state, &mstm->mgr,
 						      mstc->port, mstc->pbn);
 		if (slots < 0)