compositor-drm: Relax plane restrictions for atomic

Since we now incrementally test atomic state as we build it, we can
loosen restrictions on what we can do with planes, and let the kernel
tell us whether or not it's OK.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

libweston/compositor-drm.c

@@ -1979,7 +1979,7 @@ drm_output_prepare_scanout_view(struct drm_output_state *output_state,
 		return NULL;
 
 	/* Can't change formats with just a pageflip */
-	if (fb->format->format != output->gbm_format) {
+	if (!b->atomic_modeset && fb->format->format != output->gbm_format) {
 		drm_fb_unref(fb);
 		return NULL;
 	}
@@ -1998,15 +1998,18 @@ drm_output_prepare_scanout_view(struct drm_output_state *output_state,
 	if (!drm_plane_state_coords_for_view(state, ev))
 		goto err;
 
-	/* The legacy API does not let us perform cropping or scaling. */
-	if (state->src_x != 0 || state->src_y != 0 ||
-	    state->src_w != state->dest_w << 16 ||
-	    state->src_h != state->dest_h << 16 ||
-	    state->dest_x != 0 || state->dest_y != 0 ||
+	if (state->dest_x != 0 || state->dest_y != 0 ||
 	    state->dest_w != (unsigned) output->base.current_mode->width ||
 	    state->dest_h != (unsigned) output->base.current_mode->height)
 		goto err;
 
+	/* The legacy API does not let us perform cropping or scaling. */
+	if (!b->atomic_modeset &&
+	    (state->src_x != 0 || state->src_y != 0 ||
+	     state->src_w != state->dest_w << 16 ||
+	     state->src_h != state->dest_h << 16))
+		goto err;
+
 	/* In plane-only mode, we don't need to test the state now, as we
 	 * will only test it once at the end. */
 	return state;
@@ -3109,8 +3112,9 @@ drm_output_prepare_overlay_view(struct drm_output_state *output_state,
 			state = NULL;
 			continue;
 		}
-		if (state->src_w != state->dest_w << 16 ||
-		    state->src_h != state->dest_h << 16) {
+		if (!b->atomic_modeset &&
+		    (state->src_w != state->dest_w << 16 ||
+		     state->src_h != state->dest_h << 16)) {
 			drm_plane_state_put_back(state);
 			state = NULL;
 			continue;