compositor-drm: Introduce drm_output_state structure

Currently this doesn't actually really do anything, but will be used in
the future to track the state for both modeset and repaint requests.
Completion of the request gives us a single request-completion path for
both pageflip and vblank events.

This merges the timing paths for scanout and plane-but-but-atomic-plane
content.

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

libweston/compositor-drm.c

@@ -139,6 +139,22 @@ struct drm_property_info {
 	struct drm_property_enum_info *enum_values; /**< array of enum values */
 };
 
+/**
+ * Mode for drm_output_state_duplicate.
+ */
+enum drm_output_state_duplicate_mode {
+	DRM_OUTPUT_STATE_CLEAR_PLANES, /**< reset all planes to off */
+	DRM_OUTPUT_STATE_PRESERVE_PLANES, /**< preserve plane state */
+};
+
+/**
+ * Mode for drm_pending_state_apply and co.
+ */
+enum drm_state_apply_mode {
+	DRM_STATE_APPLY_SYNC, /**< state fully processed */
+	DRM_STATE_APPLY_ASYNC, /**< state pending event delivery */
+};
+
 struct drm_backend {
 	struct weston_backend base;
 	struct weston_compositor *compositor;
@@ -235,6 +251,23 @@ struct drm_edid {
  */
 struct drm_pending_state {
 	struct drm_backend *backend;
+	struct wl_list output_list;
+};
+
+/*
+ * Output state holds the dynamic state for one Weston output, i.e. a KMS CRTC,
+ * plus >= 1 each of encoder/connector/plane. Since everything but the planes
+ * is currently statically assigned per-output, we mainly use this to track
+ * plane state.
+ *
+ * pending_state is set when the output state is owned by a pending_state,
+ * i.e. when it is being constructed and has not yet been applied. When the
+ * output state has been applied, the owning pending_state is freed.
+ */
+struct drm_output_state {
+	struct drm_pending_state *pending_state;
+	struct drm_output *output;
+	struct wl_list link;
 };
 
 /**
@@ -328,6 +361,12 @@ struct drm_output {
 	 * repaint is flushed. */
 	struct drm_fb *fb_pending;
 
+	/* The last state submitted to the kernel for this CRTC. */
+	struct drm_output_state *state_cur;
+	/* The previously-submitted state, where the hardware has not
+	 * yet acknowledged completion of state_cur. */
+	struct drm_output_state *state_last;
+
 	struct drm_fb *dumb[2];
 	pixman_image_t *image[2];
 	int current_image;
@@ -602,6 +641,9 @@ drm_output_set_cursor(struct drm_output *output);
 static void
 drm_output_update_msc(struct drm_output *output, unsigned int seq);
 
+static void
+drm_output_destroy(struct weston_output *output_base);
+
 static int
 drm_plane_crtc_supported(struct drm_output *output, struct drm_plane *plane)
 {
@@ -902,11 +944,69 @@ drm_fb_unref(struct drm_fb *fb)
 	}
 }
 
-static int
-drm_view_transform_supported(struct weston_view *ev)
+/**
+ * Allocate a new, empty drm_output_state. This should not generally be used
+ * in the repaint cycle; see drm_output_state_duplicate.
+ */
+static struct drm_output_state *
+drm_output_state_alloc(struct drm_output *output,
+		       struct drm_pending_state *pending_state)
 {
-	return !ev->transform.enabled ||
-		(ev->transform.matrix.type < WESTON_MATRIX_TRANSFORM_ROTATE);
+	struct drm_output_state *state = zalloc(sizeof(*state));
+
+	assert(state);
+	state->output = output;
+	state->pending_state = pending_state;
+	if (pending_state)
+		wl_list_insert(&pending_state->output_list, &state->link);
+	else
+		wl_list_init(&state->link);
+
+	return state;
+}
+
+/**
+ * Duplicate an existing drm_output_state into a new one. This is generally
+ * used during the repaint cycle, to capture the existing state of an output
+ * and modify it to create a new state to be used.
+ *
+ * The mode determines whether the output will be reset to an a blank state,
+ * or an exact mirror of the current state.
+ */
+static struct drm_output_state *
+drm_output_state_duplicate(struct drm_output_state *src,
+			   struct drm_pending_state *pending_state,
+			   enum drm_output_state_duplicate_mode plane_mode)
+{
+	struct drm_output_state *dst = malloc(sizeof(*dst));
+
+	assert(dst);
+
+	/* Copy the whole structure, then individually modify the
+	 * pending_state, as well as the list link into our pending
+	 * state. */
+	*dst = *src;
+
+	dst->pending_state = pending_state;
+	if (pending_state)
+		wl_list_insert(&pending_state->output_list, &dst->link);
+	else
+		wl_list_init(&dst->link);
+
+	return dst;
+}
+
+/**
+ * Free an unused drm_output_state.
+ */
+static void
+drm_output_state_free(struct drm_output_state *state)
+{
+	if (!state)
+		return;
+
+	wl_list_remove(&state->link);
+	free(state);
 }
 
 /**
@@ -928,6 +1028,7 @@ drm_pending_state_alloc(struct drm_backend *backend)
 		return NULL;
 
 	ret->backend = backend;
+	wl_list_init(&ret->output_list);
 
 	return ret;
 }
@@ -935,19 +1036,122 @@ drm_pending_state_alloc(struct drm_backend *backend)
 /**
  * Free a drm_pending_state structure
  *
- * Frees a pending_state structure.
+ * Frees a pending_state structure, as well as any output_states connected
+ * to this pending state.
  *
  * @param pending_state Pending state structure to free
  */
 static void
 drm_pending_state_free(struct drm_pending_state *pending_state)
 {
+	struct drm_output_state *output_state, *tmp;
+
 	if (!pending_state)
 		return;
 
+	wl_list_for_each_safe(output_state, tmp, &pending_state->output_list,
+			      link) {
+		drm_output_state_free(output_state);
+	}
+
 	free(pending_state);
 }
 
+/**
+ * Find an output state in a pending state
+ *
+ * Given a pending_state structure, find the output_state for a particular
+ * output.
+ *
+ * @param pending_state Pending state structure to search
+ * @param output Output to find state for
+ * @returns Output state if present, or NULL if not
+ */
+static struct drm_output_state *
+drm_pending_state_get_output(struct drm_pending_state *pending_state,
+			     struct drm_output *output)
+{
+	struct drm_output_state *output_state;
+
+	wl_list_for_each(output_state, &pending_state->output_list, link) {
+		if (output_state->output == output)
+			return output_state;
+	}
+
+	return NULL;
+}
+
+/**
+ * Mark a drm_output_state (the output's last state) as complete. This handles
+ * any post-completion actions such as updating the repaint timer, disabling the
+ * output, and finally freeing the state.
+ */
+static void
+drm_output_update_complete(struct drm_output *output, uint32_t flags,
+			   unsigned int sec, unsigned int usec)
+{
+	struct timespec ts;
+
+	/* Stop the pageflip timer instead of rearming it here */
+	if (output->pageflip_timer)
+		wl_event_source_timer_update(output->pageflip_timer, 0);
+
+	drm_output_state_free(output->state_last);
+	output->state_last = NULL;
+
+	if (output->destroy_pending) {
+		drm_output_destroy(&output->base);
+		return;
+	} else if (output->disable_pending) {
+		weston_output_disable(&output->base);
+		output->disable_pending = 0;
+		return;
+	}
+
+	ts.tv_sec = sec;
+	ts.tv_nsec = usec * 1000;
+	weston_output_finish_frame(&output->base, &ts, flags);
+
+	/* We can't call this from frame_notify, because the output's
+	 * repaint needed flag is cleared just after that */
+	if (output->recorder)
+		weston_output_schedule_repaint(&output->base);
+}
+
+/**
+ * Mark an output state as current on the output, i.e. it has been
+ * submitted to the kernel. The mode argument determines whether this
+ * update will be applied synchronously (e.g. when calling drmModeSetCrtc),
+ * or asynchronously (in which case we wait for events to complete).
+ */
+static void
+drm_output_assign_state(struct drm_output_state *state,
+			enum drm_state_apply_mode mode)
+{
+	struct drm_output *output = state->output;
+
+	assert(!output->state_last);
+
+	if (mode == DRM_STATE_APPLY_ASYNC)
+		output->state_last = output->state_cur;
+	else
+		drm_output_state_free(output->state_cur);
+
+	wl_list_remove(&state->link);
+	wl_list_init(&state->link);
+	state->pending_state = NULL;
+
+	output->state_cur = state;
+}
+
+
+static int
+drm_view_transform_supported(struct weston_view *ev)
+{
+	return !ev->transform.enabled ||
+		(ev->transform.matrix.type < WESTON_MATRIX_TRANSFORM_ROTATE);
+}
+
 static uint32_t
 drm_output_check_scanout_format(struct drm_output *output,
 				struct weston_surface *es, struct gbm_bo *bo)
@@ -979,9 +1183,10 @@ drm_output_check_scanout_format(struct drm_output *output,
 }
 
 static struct weston_plane *
-drm_output_prepare_scanout_view(struct drm_output *output,
+drm_output_prepare_scanout_view(struct drm_output_state *output_state,
 				struct weston_view *ev)
 {
+	struct drm_output *output = output_state->output;
 	struct drm_backend *b = to_drm_backend(output->base.compositor);
 	struct weston_buffer *buffer = ev->surface->buffer_ref.buffer;
 	struct weston_buffer_viewport *viewport = &ev->surface->buffer_viewport;
@@ -1048,8 +1253,9 @@ drm_output_prepare_scanout_view(struct drm_output *output,
 }
 
 static struct drm_fb *
-drm_output_render_gl(struct drm_output *output, pixman_region32_t *damage)
+drm_output_render_gl(struct drm_output_state *state, pixman_region32_t *damage)
 {
+	struct drm_output *output = state->output;
 	struct drm_backend *b = to_drm_backend(output->base.compositor);
 	struct gbm_bo *bo;
 	struct drm_fb *ret;
@@ -1075,8 +1281,10 @@ drm_output_render_gl(struct drm_output *output, pixman_region32_t *damage)
 }
 
 static struct drm_fb *
-drm_output_render_pixman(struct drm_output *output, pixman_region32_t *damage)
+drm_output_render_pixman(struct drm_output_state *state,
+			 pixman_region32_t *damage)
 {
+	struct drm_output *output = state->output;
 	struct weston_compositor *ec = output->base.compositor;
 	pixman_region32_t total_damage, previous_damage;
 
@@ -1102,8 +1310,9 @@ drm_output_render_pixman(struct drm_output *output, pixman_region32_t *damage)
 }
 
 static void
-drm_output_render(struct drm_output *output, pixman_region32_t *damage)
+drm_output_render(struct drm_output_state *state, pixman_region32_t *damage)
 {
+	struct drm_output *output = state->output;
 	struct weston_compositor *c = output->base.compositor;
 	struct drm_backend *b = to_drm_backend(c);
 	struct drm_fb *fb;
@@ -1114,9 +1323,9 @@ drm_output_render(struct drm_output *output, pixman_region32_t *damage)
 		return;
 
 	if (b->use_pixman)
-		fb = drm_output_render_pixman(output, damage);
+		fb = drm_output_render_pixman(state, damage);
 	else
-		fb = drm_output_render_gl(output, damage);
+		fb = drm_output_render_gl(state, damage);
 
 	if (!fb)
 		return;
@@ -1178,6 +1387,8 @@ drm_output_repaint(struct weston_output *output_base,
 		   pixman_region32_t *damage,
 		   void *repaint_data)
 {
+	struct drm_pending_state *pending_state = repaint_data;
+	struct drm_output_state *state = NULL;
 	struct drm_output *output = to_drm_output(output_base);
 	struct drm_backend *backend =
 		to_drm_backend(output->base.compositor);
@@ -1186,7 +1397,18 @@ drm_output_repaint(struct weston_output *output_base,
 	int ret = 0;
 
 	if (output->disable_pending || output->destroy_pending)
-		return -1;
+		goto err;
+
+	assert(!output->state_last);
+
+	/* If planes have been disabled in the core, we might not have
+	 * hit assign_planes at all, so might not have valid output state
+	 * here. */
+	state = drm_pending_state_get_output(pending_state, output);
+	if (!state)
+		state = drm_output_state_duplicate(output->state_cur,
+						   pending_state,
+						   DRM_OUTPUT_STATE_CLEAR_PLANES);
 
 	assert(!output->fb_last);
 
@@ -1200,9 +1422,9 @@ drm_output_repaint(struct weston_output *output_base,
 		output->cursor_plane.y = INT32_MIN;
 	}
 
-	drm_output_render(output, damage);
+	drm_output_render(state, damage);
 	if (!output->fb_pending)
-		return -1;
+		goto err;
 
 	mode = container_of(output->base.current_mode, struct drm_mode, base);
 	if (output->state_invalid || !output->fb_current ||
@@ -1213,7 +1435,7 @@ drm_output_repaint(struct weston_output *output_base,
 				     &mode->mode_info);
 		if (ret) {
 			weston_log("set mode failed: %m\n");
-			goto err_pageflip;
+			goto err;
 		}
 		output_base->set_dpms(output_base, WESTON_DPMS_ON);
 
@@ -1224,7 +1446,7 @@ drm_output_repaint(struct weston_output *output_base,
 			    output->fb_pending->fb_id,
 			    DRM_MODE_PAGE_FLIP_EVENT, output) < 0) {
 		weston_log("queueing pageflip failed: %m\n");
-		goto err_pageflip;
+		goto err;
 	}
 
 	output->fb_last = output->fb_current;
@@ -1292,12 +1514,13 @@ drm_output_repaint(struct weston_output *output_base,
 
 	return 0;
 
-err_pageflip:
+err:
 	output->cursor_view = NULL;
 	if (output->fb_pending) {
 		drm_fb_unref(output->fb_pending);
 		output->fb_pending = NULL;
 	}
+	drm_output_state_free(state);
 
 	return -1;
 }
@@ -1306,6 +1529,8 @@ static void
 drm_output_start_repaint_loop(struct weston_output *output_base)
 {
 	struct drm_output *output = to_drm_output(output_base);
+	struct drm_pending_state *pending_state = NULL;
+	struct drm_output_state *state;
 	struct drm_backend *backend =
 		to_drm_backend(output_base->compositor);
 	uint32_t fb_id;
@@ -1366,6 +1591,11 @@ drm_output_start_repaint_loop(struct weston_output *output_base)
 
 	assert(!output->page_flip_pending);
 	assert(!output->fb_last);
+	assert(!output->state_last);
+
+	pending_state = drm_pending_state_alloc(backend);
+	state = drm_output_state_duplicate(output->state_cur, pending_state,
+					   DRM_OUTPUT_STATE_PRESERVE_PLANES);
 
 	if (drmModePageFlip(backend->drm.fd, output->crtc_id, fb_id,
 			    DRM_MODE_PAGE_FLIP_EVENT, output) < 0) {
@@ -1380,9 +1610,14 @@ drm_output_start_repaint_loop(struct weston_output *output_base)
 	output->fb_last = drm_fb_ref(output->fb_current);
 	output->page_flip_pending = 1;
 
+	drm_output_assign_state(state, DRM_STATE_APPLY_ASYNC);
+	drm_pending_state_free(pending_state);
+
 	return;
 
 finish_frame:
+	drm_pending_state_free(pending_state);
+
 	/* if we cannot page-flip, immediately finish frame */
 	weston_output_finish_frame(output_base, NULL,
 				   WP_PRESENTATION_FEEDBACK_INVALID);
@@ -1405,7 +1640,6 @@ vblank_handler(int fd, unsigned int frame, unsigned int sec, unsigned int usec,
 {
 	struct drm_plane *s = (struct drm_plane *)data;
 	struct drm_output *output = s->output;
-	struct timespec ts;
 	uint32_t flags = WP_PRESENTATION_FEEDBACK_KIND_HW_COMPLETION |
 			 WP_PRESENTATION_FEEDBACK_KIND_HW_CLOCK;
 
@@ -1417,26 +1651,17 @@ vblank_handler(int fd, unsigned int frame, unsigned int sec, unsigned int usec,
 	drm_fb_unref(s->fb_last);
 	s->fb_last = NULL;
 
-	if (!output->page_flip_pending && !output->vblank_pending) {
-		/* Stop the pageflip timer instead of rearming it here */
-		if (output->pageflip_timer)
-			wl_event_source_timer_update(output->pageflip_timer, 0);
+	if (output->page_flip_pending || output->vblank_pending)
+		return;
 
-		ts.tv_sec = sec;
-		ts.tv_nsec = usec * 1000;
-		weston_output_finish_frame(&output->base, &ts, flags);
-	}
+	drm_output_update_complete(output, flags, sec, usec);
 }
 
-static void
-drm_output_destroy(struct weston_output *base);
-
 static void
 page_flip_handler(int fd, unsigned int frame,
 		  unsigned int sec, unsigned int usec, void *data)
 {
 	struct drm_output *output = data;
-	struct timespec ts;
 	uint32_t flags = WP_PRESENTATION_FEEDBACK_KIND_VSYNC |
 			 WP_PRESENTATION_FEEDBACK_KIND_HW_COMPLETION |
 			 WP_PRESENTATION_FEEDBACK_KIND_HW_CLOCK;
@@ -1449,30 +1674,18 @@ page_flip_handler(int fd, unsigned int frame,
 	drm_fb_unref(output->fb_last);
 	output->fb_last = NULL;
 
-	if (output->destroy_pending)
-		drm_output_destroy(&output->base);
-	else if (output->disable_pending)
-		weston_output_disable(&output->base);
-	else if (!output->vblank_pending) {
-		/* Stop the pageflip timer instead of rearming it here */
-		if (output->pageflip_timer)
-			wl_event_source_timer_update(output->pageflip_timer, 0);
-
-		ts.tv_sec = sec;
-		ts.tv_nsec = usec * 1000;
-		weston_output_finish_frame(&output->base, &ts, flags);
-
-		/* We can't call this from frame_notify, because the output's
-		 * repaint needed flag is cleared just after that */
-		if (output->recorder)
-			weston_output_schedule_repaint(&output->base);
-	}
+	if (output->vblank_pending)
+		return;
+
+	drm_output_update_complete(output, flags, sec, usec);
 }
 
 /**
  * Begin a new repaint cycle
  *
- * Called by the core compositor at the beginning of a repaint cycle.
+ * Called by the core compositor at the beginning of a repaint cycle. Creates
+ * a new pending_state structure to own any output state created by individual
+ * output repaint functions until the repaint is flushed or cancelled.
  */
 static void *
 drm_repaint_begin(struct weston_compositor *compositor)
@@ -1490,13 +1703,22 @@ drm_repaint_begin(struct weston_compositor *compositor)
  * Flush a repaint set
  *
  * Called by the core compositor when a repaint cycle has been completed
- * and should be flushed.
+ * and should be flushed. Frees the pending state, transitioning ownership
+ * of the output state from the pending state, to the update itself. When
+ * the update completes (see drm_output_update_complete), the output
+ * state will be freed.
  */
 static void
 drm_repaint_flush(struct weston_compositor *compositor, void *repaint_data)
 {
 	struct drm_backend *b = to_drm_backend(compositor);
 	struct drm_pending_state *pending_state = repaint_data;
+	struct drm_output_state *output_state, *tmp;
+
+	wl_list_for_each_safe(output_state, tmp, &pending_state->output_list,
+			      link) {
+		drm_output_assign_state(output_state, DRM_STATE_APPLY_ASYNC);
+	}
 
 	drm_pending_state_free(pending_state);
 	b->repaint_data = NULL;
@@ -1548,9 +1770,10 @@ drm_output_check_plane_format(struct drm_plane *p,
 }
 
 static struct weston_plane *
-drm_output_prepare_overlay_view(struct drm_output *output,
+drm_output_prepare_overlay_view(struct drm_output_state *output_state,
 				struct weston_view *ev)
 {
+	struct drm_output *output = output_state->output;
 	struct weston_compositor *ec = output->base.compositor;
 	struct drm_backend *b = to_drm_backend(ec);
 	struct weston_buffer_viewport *viewport = &ev->surface->buffer_viewport;
@@ -1734,9 +1957,10 @@ drm_output_prepare_overlay_view(struct drm_output *output,
 }
 
 static struct weston_plane *
-drm_output_prepare_cursor_view(struct drm_output *output,
+drm_output_prepare_cursor_view(struct drm_output_state *output_state,
 			       struct weston_view *ev)
 {
+	struct drm_output *output = output_state->output;
 	struct drm_backend *b = to_drm_backend(output->base.compositor);
 	struct weston_buffer_viewport *viewport = &ev->surface->buffer_viewport;
 	struct wl_shm_buffer *shmbuf;
@@ -1867,12 +2091,19 @@ 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 weston_view *ev, *next;
 	pixman_region32_t overlap, surface_overlap;
 	struct weston_plane *primary, *next_plane;
 	bool picked_scanout = false;
 
+	assert(!output->state_last);
+	state = drm_output_state_duplicate(output->state_cur,
+					   pending_state,
+					   DRM_OUTPUT_STATE_CLEAR_PLANES);
+
 	/*
 	 * Find a surface for each sprite in the output using some heuristics:
 	 * 1) size
@@ -1921,19 +2152,19 @@ drm_assign_planes(struct weston_output *output_base, void *repaint_data)
 		if (pixman_region32_not_empty(&surface_overlap) || picked_scanout)
 			next_plane = primary;
 		if (next_plane == NULL)
-			next_plane = drm_output_prepare_cursor_view(output, ev);
+			next_plane = drm_output_prepare_cursor_view(state, ev);
 
 		/* If a higher-stacked view already got assigned to scanout, it's incorrect to
 		 * assign a subsequent (lower-stacked) view to scanout.
 		 */
 		if (next_plane == NULL) {
-			next_plane = drm_output_prepare_scanout_view(output, ev);
+			next_plane = drm_output_prepare_scanout_view(state, ev);
 			if (next_plane)
 				picked_scanout = true;
 		}
 
 		if (next_plane == NULL)
-			next_plane = drm_output_prepare_overlay_view(output, ev);
+			next_plane = drm_output_prepare_overlay_view(state, ev);
 
 		if (next_plane == NULL)
 			next_plane = primary;
@@ -3260,7 +3491,7 @@ drm_output_destroy(struct weston_output *base)
 	struct drm_mode *drm_mode, *next;
 	drmModeCrtcPtr origcrtc = output->original_crtc;
 
-	if (output->page_flip_pending) {
+	if (output->page_flip_pending || output->vblank_pending) {
 		output->destroy_pending = 1;
 		weston_log("destroy output while page flip pending\n");
 		return;
@@ -3295,6 +3526,9 @@ drm_output_destroy(struct weston_output *base)
 	if (output->backlight)
 		backlight_destroy(output->backlight);
 
+	assert(!output->state_last);
+	drm_output_state_free(output->state_cur);
+
 	free(output);
 }
 
@@ -3304,7 +3538,7 @@ drm_output_disable(struct weston_output *base)
 	struct drm_output *output = to_drm_output(base);
 	struct drm_backend *b = to_drm_backend(base->compositor);
 
-	if (output->page_flip_pending) {
+	if (output->page_flip_pending || output->vblank_pending) {
 		output->disable_pending = 1;
 		return -1;
 	}
@@ -3312,12 +3546,19 @@ drm_output_disable(struct weston_output *base)
 	if (output->base.enabled)
 		drm_output_deinit(&output->base);
 
+	assert(!output->fb_last);
+	assert(!output->fb_current);
+	assert(!output->fb_pending);
+
 	output->disable_pending = 0;
 
 	weston_log("Disabling output %s\n", output->base.name);
 	drmModeSetCrtc(b->drm.fd, output->crtc_id,
 		       0, 0, 0, 0, 0, NULL);
 
+	drm_output_state_free(output->state_cur);
+	output->state_cur = drm_output_state_alloc(output, NULL);
+
 	return 0;
 }
 
@@ -3404,6 +3645,8 @@ create_output_for_connector(struct drm_backend *b,
 	    output->connector->connector_type == DRM_MODE_CONNECTOR_eDP)
 		output->base.connection_internal = true;
 
+	output->state_cur = drm_output_state_alloc(output, NULL);
+
 	output->base.mm_width = output->connector->mmWidth;
 	output->base.mm_height = output->connector->mmHeight;