drm/amd/display: Complete TODO item: use new DRM iterator

Abandon new_crtcs array and use for_each_new iterator to acquire new
crtcs.
Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -4034,10 +4034,8 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 	struct amdgpu_display_manager *dm = &adev->dm;
 	struct dm_atomic_state *dm_state;
 	uint32_t i, j;
-	uint32_t new_crtcs_count = 0;
 	struct drm_crtc *crtc;
 	struct drm_crtc_state *old_crtc_state, *new_crtc_state;
-	struct amdgpu_crtc *new_crtcs[MAX_STREAMS];
 	unsigned long flags;
 	bool wait_for_vblank = true;
 	struct drm_connector *connector;
@@ -4096,25 +4094,9 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 				continue;
 			}
 
-
 			if (dm_old_crtc_state->stream)
 				remove_stream(adev, acrtc, dm_old_crtc_state->stream);
 
-
-			/*
-			 * this loop saves set mode crtcs
-			 * we needed to enable vblanks once all
-			 * resources acquired in dc after dc_commit_streams
-			 */
-
-			/*TODO move all this into dm_crtc_state, get rid of
-			 * new_crtcs array and use old and new atomic states
-			 * instead
-			 */
-			new_crtcs[new_crtcs_count] = acrtc;
-			new_crtcs_count++;
-
-			new_crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
 			acrtc->enabled = true;
 			acrtc->hw_mode = new_crtc_state->mode;
 			crtc->hwmode = new_crtc_state->mode;
@@ -4242,18 +4224,28 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 			dm_error("%s: Failed to update stream scaling!\n", __func__);
 	}
 
-	for (i = 0; i < new_crtcs_count; i++) {
+	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state,
+			new_crtc_state, i) {
 		/*
 		 * loop to enable interrupts on newly arrived crtc
 		 */
-		struct amdgpu_crtc *acrtc = new_crtcs[i];
+		struct amdgpu_crtc *acrtc = to_amdgpu_crtc(crtc);
+		bool modeset_needed;
 
-		new_crtc_state = drm_atomic_get_new_crtc_state(state, &acrtc->base);
 		dm_new_crtc_state = to_dm_crtc_state(new_crtc_state);
+		dm_old_crtc_state = to_dm_crtc_state(old_crtc_state);
+		modeset_needed = modeset_required(
+				new_crtc_state,
+				dm_new_crtc_state->stream,
+				dm_old_crtc_state->stream);
+
+		if (dm_new_crtc_state->stream == NULL || !modeset_needed)
+			continue;
 
 		if (adev->dm.freesync_module)
 			mod_freesync_notify_mode_change(
-				adev->dm.freesync_module, &dm_new_crtc_state->stream, 1);
+				adev->dm.freesync_module,
+				&dm_new_crtc_state->stream, 1);
 
 		manage_dm_interrupts(adev, acrtc, true);
 	}