compositor-drm: Split drm_assign_planes in two

Move drm_assign_planes into two functions: one which proposes a plane
configuration, and another which applies that state to the Weston
internal structures. This will be used to try multiple configurations
and see which is supported.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Tested-by: Emre Ucan <eucan@de.adit-jv.com>

libweston/compositor-drm.c

@@ -407,6 +407,8 @@ struct drm_plane_state {
 
 	struct drm_fb *fb;
 
+	struct weston_view *ev; /**< maintained for drm_assign_planes only */
+
 	int32_t src_x, src_y;
 	uint32_t src_w, src_h;
 	int32_t dest_x, dest_y;
@@ -1984,6 +1986,7 @@ drm_output_prepare_scanout_view(struct drm_output_state *output_state,
 	}
 
 	state->fb = fb;
+	state->ev = ev;
 	state->output = output;
 	if (!drm_plane_state_coords_for_view(state, ev))
 		goto err;
@@ -3055,6 +3058,7 @@ drm_output_prepare_overlay_view(struct drm_output_state *output_state,
 	}
 
 	state->fb = fb;
+	state->ev = ev;
 	state->output = output;
 
 	if (!drm_plane_state_coords_for_view(state, ev))
@@ -3182,6 +3186,7 @@ drm_output_prepare_cursor_view(struct drm_output_state *output_state,
 	}
 
 	output->cursor_view = ev;
+	plane_state->ev = ev;
 
 	plane_state->fb =
 		drm_fb_ref(output->gbm_cursor_fb[output->current_cursor]);
@@ -3258,40 +3263,15 @@ err:
 	drmModeSetCursor(b->drm.fd, output->crtc_id, 0, 0, 0);
 }
 
-/*
+static struct drm_output_state *
- * Get the aspect-ratio from drmModeModeInfo mode flags.
+drm_output_propose_state(struct weston_output *output_base,
- *
+			 struct drm_pending_state *pending_state)
- * @param drm_mode_flags- flags from drmModeModeInfo structure.
- * @returns aspect-ratio as encoded in enum 'weston_mode_aspect_ratio'.
- */
-static enum weston_mode_aspect_ratio
-drm_to_weston_mode_aspect_ratio(uint32_t drm_mode_flags)
-{
-	return (drm_mode_flags & DRM_MODE_FLAG_PIC_AR_MASK) >>
-		DRM_MODE_FLAG_PIC_AR_BITS_POS;
-}
-
-static const char *
-aspect_ratio_to_string(enum weston_mode_aspect_ratio ratio)
-{
-	if (ratio < 0 || ratio >= ARRAY_LENGTH(aspect_ratio_as_string) ||
-	    !aspect_ratio_as_string[ratio])
-		return " (unknown aspect ratio)";
-
-	return aspect_ratio_as_string[ratio];
-}
-
-static void
-drm_assign_planes(struct weston_output *output_base, void *repaint_data)
 {
-	struct drm_backend *b = to_drm_backend(output_base->compositor);
-	struct drm_pending_state *pending_state = repaint_data;
 	struct drm_output *output = to_drm_output(output_base);
 	struct drm_output_state *state;
-	struct drm_plane_state *plane_state;
 	struct weston_view *ev;
 	pixman_region32_t surface_overlap, renderer_region;
-	struct weston_plane *primary, *next_plane;
+	struct weston_plane *primary = &output_base->compositor->primary_plane;
 
 	assert(!output->state_last);
 	state = drm_output_state_duplicate(output->state_cur,
@@ -3312,35 +3292,21 @@ drm_assign_planes(struct weston_output *output_base, void *repaint_data)
 	 * as we do for flipping full screen surfaces.
 	 */
 	pixman_region32_init(&renderer_region);
-	primary = &output_base->compositor->primary_plane;
 
 	wl_list_for_each(ev, &output_base->compositor->view_list, link) {
-		struct weston_surface *es = ev->surface;
+		struct weston_plane *next_plane = NULL;
-
-		/* Test whether this buffer can ever go into a plane:
-		 * non-shm, or small enough to be a cursor.
-		 *
-		 * Also, keep a reference when using the pixman renderer.
-		 * That makes it possible to do a seamless switch to the GL
-		 * renderer and since the pixman renderer keeps a reference
-		 * to the buffer anyway, there is no side effects.
-		 */
-		if (b->use_pixman ||
-		    (es->buffer_ref.buffer &&
-		    (!wl_shm_buffer_get(es->buffer_ref.buffer->resource) ||
-		     (ev->surface->width <= b->cursor_width &&
-		      ev->surface->height <= b->cursor_height))))
-			es->keep_buffer = true;
-		else
-			es->keep_buffer = false;
 
+		/* Since we process views from top to bottom, we know that if
+		 * the view intersects the calculated renderer region, it must
+		 * be part of, or occluded by, it, and cannot go on a plane. */
 		pixman_region32_init(&surface_overlap);
 		pixman_region32_intersect(&surface_overlap, &renderer_region,
 					  &ev->transform.boundingbox);
 
-		next_plane = NULL;
 		if (pixman_region32_not_empty(&surface_overlap))
 			next_plane = primary;
+		pixman_region32_fini(&surface_overlap);
+
 		if (next_plane == NULL)
 			next_plane = drm_output_prepare_cursor_view(state, ev);
 
@@ -3353,17 +3319,70 @@ drm_assign_planes(struct weston_output *output_base, void *repaint_data)
 		if (next_plane == NULL)
 			next_plane = primary;
 
-		weston_view_move_to_plane(ev, next_plane);
-
 		if (next_plane == primary)
 			pixman_region32_union(&renderer_region,
 					      &renderer_region,
 					      &ev->transform.boundingbox);
+	}
+	pixman_region32_fini(&renderer_region);
+
+	return state;
+}
+
+static void
+drm_assign_planes(struct weston_output *output_base, void *repaint_data)
+{
+	struct drm_backend *b = to_drm_backend(output_base->compositor);
+	struct drm_pending_state *pending_state = repaint_data;
+	struct drm_output *output = to_drm_output(output_base);
+	struct drm_output_state *state;
+	struct drm_plane_state *plane_state;
+	struct weston_view *ev;
+	struct weston_plane *primary = &output_base->compositor->primary_plane;
+
+	state = drm_output_propose_state(output_base, pending_state);
+
+	wl_list_for_each(ev, &output_base->compositor->view_list, link) {
+		struct drm_plane *target_plane = NULL;
+
+		/* Test whether this buffer can ever go into a plane:
+		 * non-shm, or small enough to be a cursor.
+		 *
+		 * Also, keep a reference when using the pixman renderer.
+		 * That makes it possible to do a seamless switch to the GL
+		 * renderer and since the pixman renderer keeps a reference
+		 * to the buffer anyway, there is no side effects.
+		 */
+		if (b->use_pixman ||
+		    (ev->surface->buffer_ref.buffer &&
+		    (!wl_shm_buffer_get(ev->surface->buffer_ref.buffer->resource) ||
+		     (ev->surface->width <= b->cursor_width &&
+		      ev->surface->height <= b->cursor_height))))
+			ev->surface->keep_buffer = true;
+		else
+			ev->surface->keep_buffer = false;
+
+		/* This is a bit unpleasant, but lacking a temporary place to
+		 * hang a plane off the view, we have to do a nested walk.
+		 * Our first-order iteration has to be planes rather than
+		 * views, because otherwise we won't reset views which were
+		 * previously on planes to being on the primary plane. */
+		wl_list_for_each(plane_state, &state->plane_list, link) {
+			if (plane_state->ev == ev) {
+				plane_state->ev = NULL;
+				target_plane = plane_state->plane;
+				break;
+			}
+		}
+
+		if (target_plane)
+			weston_view_move_to_plane(ev, &target_plane->base);
+		else
+			weston_view_move_to_plane(ev, primary);
 
-		if (next_plane == primary ||
+		if (!target_plane ||
-		    (output->cursor_plane &&
+		    target_plane->type == WDRM_PLANE_TYPE_CURSOR) {
-		     next_plane == &output->cursor_plane->base)) {
+			/* cursor plane & renderer involve a copy */
-			/* cursor plane involves a copy */
 			ev->psf_flags = 0;
 		} else {
 			/* All other planes are a direct scanout of a
@@ -3371,10 +3390,7 @@ drm_assign_planes(struct weston_output *output_base, void *repaint_data)
 			 */
 			ev->psf_flags = WP_PRESENTATION_FEEDBACK_KIND_ZERO_COPY;
 		}
-
-		pixman_region32_fini(&surface_overlap);
 	}
-	pixman_region32_fini(&renderer_region);
 
 	/* We rely on output->cursor_view being both an accurate reflection of
 	 * the cursor plane's state, but also being maintained across repaints
@@ -3390,6 +3406,29 @@ drm_assign_planes(struct weston_output *output_base, void *repaint_data)
 	}
 }
 
+/*
+ * Get the aspect-ratio from drmModeModeInfo mode flags.
+ *
+ * @param drm_mode_flags- flags from drmModeModeInfo structure.
+ * @returns aspect-ratio as encoded in enum 'weston_mode_aspect_ratio'.
+ */
+static enum weston_mode_aspect_ratio
+drm_to_weston_mode_aspect_ratio(uint32_t drm_mode_flags)
+{
+	return (drm_mode_flags & DRM_MODE_FLAG_PIC_AR_MASK) >>
+		DRM_MODE_FLAG_PIC_AR_BITS_POS;
+}
+
+static const char *
+aspect_ratio_to_string(enum weston_mode_aspect_ratio ratio)
+{
+	if (ratio < 0 || ratio >= ARRAY_LENGTH(aspect_ratio_as_string) ||
+	    !aspect_ratio_as_string[ratio])
+		return " (unknown aspect ratio)";
+
+	return aspect_ratio_as_string[ratio];
+}
+
 /**
  * Find the closest-matching mode for a given target
  *