backend/drm: introduce wlr_drm_fb

This is a type which manages gbm_surfaces and imported dmabufs in the
same place, and makes the lifetime management between the two shared. It
should lead to easier to understand code, and fewer special cases.

This also contains a fair bit of refactoring to start using this new
type.

Co-authored-by: Simon Ser <contact@emersion.fr>

3 files changed, 53 insertions, 30 deletions

diff --git a/include/backend/drm/drm.h b/include/backend/drm/drm.h
index ffd3138f..0ab4ff21 100644
--- a/include/backend/drm/drm.h
+++ b/include/backend/drm/drm.h
@@ -25,11 +25,17 @@ struct wlr_drm_plane {
 	struct wlr_drm_surface surf;
 	struct wlr_drm_surface mgpu_surf;
 
+	/* Buffer to be submitted to the kernel on the next page-flip */
+	struct wlr_drm_fb pending_fb;
+	/* Buffer submitted to the kernel, will be presented on next vblank */
+	struct wlr_drm_fb queued_fb;
+	/* Buffer currently displayed on screen */
+	struct wlr_drm_fb current_fb;
+
 	uint32_t drm_format; // ARGB8888 or XRGB8888
 	struct wlr_drm_format_set formats;
 
 	// Only used by cursor
-	float matrix[9];
 	bool cursor_enabled;
 	int32_t cursor_hotspot_x, cursor_hotspot_y;
 
@@ -124,16 +130,16 @@ struct wlr_drm_connector {
 
 	drmModeCrtc *old_crtc;
 
-	bool pageflip_pending;
 	struct wl_event_source *retry_pageflip;
 	struct wl_list link;
 
-	// Buffer submitted to the kernel but not yet displayed
-	struct wlr_buffer *pending_buffer;
-	struct gbm_bo *pending_bo;
-	// Buffer currently being displayed
-	struct wlr_buffer *current_buffer;
-	struct gbm_bo *current_bo;
+	/*
+	 * We've asked for a state change in the kernel, and yet to recieve a
+	 * notification for its completion. Currently, the kernel only has a
+	 * queue length of 1, and no way to modify your submissions after
+	 * they're sent.
+	 */
+	bool pageflip_pending;
 };
 
 struct wlr_drm_backend *get_drm_backend_from_backend(
@@ -150,6 +156,8 @@ bool set_drm_connector_gamma(struct wlr_output *output, size_t size,
 bool drm_connector_set_mode(struct wlr_output *output,
 	struct wlr_output_mode *mode);
 
+struct wlr_drm_fb *plane_get_next_fb(struct wlr_drm_plane *plane);
+
 bool legacy_crtc_set_cursor(struct wlr_drm_backend *drm,
 	struct wlr_drm_crtc *crtc, struct gbm_bo *bo);
 bool legacy_crtc_move_cursor(struct wlr_drm_backend *drm,
diff --git a/include/backend/drm/renderer.h b/include/backend/drm/renderer.h
index 567cf95e..bfccf9d5 100644
--- a/include/backend/drm/renderer.h
+++ b/include/backend/drm/renderer.h
@@ -10,6 +10,7 @@
 
 struct wlr_drm_backend;
 struct wlr_drm_plane;
+struct wlr_buffer;
 
 struct wlr_drm_renderer {
 	int fd;
@@ -29,33 +30,48 @@ struct wlr_drm_surface {
 
 	struct gbm_surface *gbm;
 	EGLSurface egl;
+};
+
+enum wlr_drm_fb_type {
+	WLR_DRM_FB_TYPE_NONE,
+	WLR_DRM_FB_TYPE_SURFACE,
+	WLR_DRM_FB_TYPE_WLR_BUFFER
+};
+
+struct wlr_drm_fb {
+	enum wlr_drm_fb_type type;
+	struct gbm_bo *bo;
+
+	struct wlr_drm_surface *mgpu_surf;
+	struct gbm_bo *mgpu_bo;
 
-	struct gbm_bo *front;
-	struct gbm_bo *back;
+	union {
+		struct wlr_drm_surface *surf;
+		struct wlr_buffer *wlr_buf;
+	};
 };
 
 bool init_drm_renderer(struct wlr_drm_backend *drm,
 	struct wlr_drm_renderer *renderer, wlr_renderer_create_func_t create_render);
 void finish_drm_renderer(struct wlr_drm_renderer *renderer);
 
-bool init_drm_surface(struct wlr_drm_surface *surf,
-	struct wlr_drm_renderer *renderer, uint32_t width, uint32_t height,
-	uint32_t format, struct wlr_drm_format_set *set, uint32_t flags);
-
-bool init_drm_plane_surfaces(struct wlr_drm_plane *plane,
-	struct wlr_drm_backend *drm, int32_t width, uint32_t height,
-	uint32_t format, bool with_modifiers);
-
-void finish_drm_surface(struct wlr_drm_surface *surf);
-bool make_drm_surface_current(struct wlr_drm_surface *surf, int *buffer_age);
-struct gbm_bo *swap_drm_surface_buffers(struct wlr_drm_surface *surf,
-	pixman_region32_t *damage);
-struct gbm_bo *get_drm_surface_front(struct wlr_drm_surface *surf);
-void post_drm_surface(struct wlr_drm_surface *surf);
-struct gbm_bo *copy_drm_surface_mgpu(struct wlr_drm_surface *dest,
-	struct gbm_bo *src);
-struct gbm_bo *import_gbm_bo(struct wlr_drm_renderer *renderer,
-	struct wlr_dmabuf_attributes *attribs);
+bool drm_surface_make_current(struct wlr_drm_surface *surf, int *buffer_age);
 bool export_drm_bo(struct gbm_bo *bo, struct wlr_dmabuf_attributes *attribs);
 
+void drm_fb_clear(struct wlr_drm_fb *fb);
+bool drm_fb_lock_surface(struct wlr_drm_fb *fb, struct wlr_drm_surface *surf);
+bool drm_fb_import_wlr(struct wlr_drm_fb *fb, struct wlr_drm_renderer *renderer,
+		struct wlr_buffer *buf, struct wlr_drm_format_set *set);
+
+void drm_fb_move(struct wlr_drm_fb *new, struct wlr_drm_fb *old);
+
+bool drm_surface_render_black_frame(struct wlr_drm_surface *surf);
+struct gbm_bo *drm_fb_acquire(struct wlr_drm_fb *fb, struct wlr_drm_backend *drm,
+		struct wlr_drm_surface *mgpu);
+
+bool drm_plane_init_surface(struct wlr_drm_plane *plane,
+		struct wlr_drm_backend *drm, int32_t width, uint32_t height,
+		uint32_t format, uint32_t flags, bool with_modifiers);
+void drm_plane_finish_surface(struct wlr_drm_plane *plane);
+
 #endif
diff --git a/include/backend/drm/util.h b/include/backend/drm/util.h
index 2d9d11f4..15895ec6 100644
--- a/include/backend/drm/util.h
+++ b/include/backend/drm/util.h
@@ -14,8 +14,7 @@ void parse_edid(struct wlr_output *restrict output, size_t len,
 // Returns the string representation of a DRM output type
 const char *conn_get_name(uint32_t type_id);
 // Returns the DRM framebuffer id for a gbm_bo
-uint32_t get_fb_for_bo(struct gbm_bo *bo, uint32_t drm_format,
-	bool with_modifiers);
+uint32_t get_fb_for_bo(struct gbm_bo *bo, bool with_modifiers);
 
 // Part of match_obj
 enum {