backend/wayland: add support for direct scan-out

Closes: https://github.com/swaywm/wlroots/issues/1830

backend/wayland/backend.c

@@ -5,6 +5,7 @@
 
 #include <wlr/config.h>
 
+#include <drm_fourcc.h>
 #include <wayland-server-core.h>
 
 #include <wlr/backend/interface.h>
@@ -16,8 +17,9 @@
 
 #include "backend/wayland.h"
 #include "util/signal.h"
-#include "xdg-decoration-unstable-v1-client-protocol.h"
+#include "linux-dmabuf-unstable-v1-client-protocol.h"
 #include "pointer-gestures-unstable-v1-client-protocol.h"
+#include "xdg-decoration-unstable-v1-client-protocol.h"
 #include "xdg-shell-client-protocol.h"
 #include "tablet-unstable-v2-client-protocol.h"
 
@@ -59,6 +61,29 @@ static const struct xdg_wm_base_listener xdg_wm_base_listener = {
 	xdg_wm_base_handle_ping,
 };
 
+static void linux_dmabuf_v1_handle_format(void *data,
+		struct zwp_linux_dmabuf_v1 *linux_dmabuf_v1, uint32_t format) {
+	// Note, this event is deprecated
+	struct wlr_wl_backend *wl = data;
+
+	wlr_drm_format_set_add(&wl->linux_dmabuf_v1_formats, format,
+		DRM_FORMAT_MOD_INVALID);
+}
+
+static void linux_dmabuf_v1_handle_modifier(void *data,
+		struct zwp_linux_dmabuf_v1 *linux_dmabuf_v1, uint32_t format,
+		uint32_t modifier_hi, uint32_t modifier_lo) {
+	struct wlr_wl_backend *wl = data;
+
+	uint64_t modifier = ((uint64_t)modifier_hi << 32) | modifier_lo;
+	wlr_drm_format_set_add(&wl->linux_dmabuf_v1_formats, format, modifier);
+}
+
+static const struct zwp_linux_dmabuf_v1_listener linux_dmabuf_v1_listener = {
+	.format = linux_dmabuf_v1_handle_format,
+	.modifier = linux_dmabuf_v1_handle_modifier,
+};
+
 static void registry_global(void *data, struct wl_registry *registry,
 		uint32_t name, const char *iface, uint32_t version) {
 	struct wlr_wl_backend *wl = data;
@@ -85,6 +110,12 @@ static void registry_global(void *data, struct wl_registry *registry,
 	} else if (strcmp(iface, zwp_tablet_manager_v2_interface.name) == 0) {
 		wl->tablet_manager = wl_registry_bind(registry, name,
 			&zwp_tablet_manager_v2_interface, 1);
+	} else if (strcmp(iface, zwp_linux_dmabuf_v1_interface.name) == 0 &&
+			version >= 3) {
+		wl->zwp_linux_dmabuf_v1 = wl_registry_bind(registry, name,
+			&zwp_linux_dmabuf_v1_interface, 3);
+		zwp_linux_dmabuf_v1_add_listener(wl->zwp_linux_dmabuf_v1,
+			&linux_dmabuf_v1_listener, wl);
 	}
 }
 
@@ -153,6 +184,8 @@ static void backend_destroy(struct wlr_backend *backend) {
 	wlr_renderer_destroy(wl->renderer);
 	wlr_egl_finish(&wl->egl);
 
+	wlr_drm_format_set_finish(&wl->linux_dmabuf_v1_formats);
+
 	if (wl->pointer) {
 		wl_pointer_destroy(wl->pointer);
 	}
@@ -165,6 +198,9 @@ static void backend_destroy(struct wlr_backend *backend) {
 	if (wl->zwp_pointer_gestures_v1) {
 		zwp_pointer_gestures_v1_destroy(wl->zwp_pointer_gestures_v1);
 	}
+	if (wl->zwp_linux_dmabuf_v1) {
+		zwp_linux_dmabuf_v1_destroy(wl->zwp_linux_dmabuf_v1);
+	}
 	xdg_wm_base_destroy(wl->xdg_wm_base);
 	wl_compositor_destroy(wl->compositor);
 	wl_registry_destroy(wl->registry);

backend/wayland/output.c

@@ -16,6 +16,7 @@
 
 #include "backend/wayland.h"
 #include "util/signal.h"
+#include "linux-dmabuf-unstable-v1-client-protocol.h"
 #include "xdg-decoration-unstable-v1-client-protocol.h"
 #include "xdg-shell-client-protocol.h"
 
@@ -59,6 +60,59 @@ static bool output_attach_render(struct wlr_output *wlr_output,
 		buffer_age);
 }
 
+static bool output_attach_buffer(struct wlr_output *wlr_output,
+		struct wlr_buffer *buffer) {
+	struct wlr_wl_output *output =
+		get_wl_output_from_output(wlr_output);
+	struct wlr_wl_backend *wl = output->backend;
+
+	struct wlr_dmabuf_attributes attribs;
+	if (!wlr_buffer_get_dmabuf(buffer, &attribs)) {
+		return false;
+	}
+
+	if (attribs.width != wlr_output->width ||
+			attribs.height != wlr_output->height) {
+		return false;
+	}
+
+	if (!wlr_drm_format_set_has(&wl->linux_dmabuf_v1_formats,
+			attribs.format, attribs.modifier)) {
+		return false;
+	}
+
+	uint32_t modifier_hi = attribs.modifier >> 32;
+	uint32_t modifier_lo = (uint32_t)attribs.modifier;
+	struct zwp_linux_buffer_params_v1 *params =
+		zwp_linux_dmabuf_v1_create_params(wl->zwp_linux_dmabuf_v1);
+	for (int i = 0; i < attribs.n_planes; i++) {
+		zwp_linux_buffer_params_v1_add(params, attribs.fd[i], i,
+			attribs.offset[i], attribs.stride[i], modifier_hi, modifier_lo);
+	}
+
+	uint32_t flags = 0;
+	if (attribs.flags & WLR_DMABUF_ATTRIBUTES_FLAGS_Y_INVERT) {
+		flags |= ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_Y_INVERT;
+	}
+	if (attribs.flags & WLR_DMABUF_ATTRIBUTES_FLAGS_INTERLACED) {
+		flags |= ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_INTERLACED;
+	}
+	if (attribs.flags & WLR_DMABUF_ATTRIBUTES_FLAGS_BOTTOM_FIRST) {
+		flags |= ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_BOTTOM_FIRST;
+	}
+	struct wl_buffer *wl_buffer = zwp_linux_buffer_params_v1_create_immed(
+		params, attribs.width, attribs.height, attribs.format, flags);
+	// TODO: handle create() errors
+
+	wl_surface_attach(output->surface, wl_buffer, 0, 0);
+
+	if (output->pending_wl_buffer != NULL) {
+		wl_buffer_destroy(output->pending_wl_buffer);
+	}
+	output->pending_wl_buffer = wl_buffer;
+	return true;
+}
+
 static bool output_commit(struct wlr_output *wlr_output) {
 	struct wlr_wl_output *output =
 		get_wl_output_from_output(wlr_output);
@@ -76,13 +130,46 @@ static bool output_commit(struct wlr_output *wlr_output) {
 		damage = &wlr_output->pending.damage;
 	}
 
-	if (!wlr_egl_swap_buffers(&output->backend->egl,
-			output->egl_surface, damage)) {
-		return false;
+	wlr_buffer_unref(output->current_buffer);
+	output->current_buffer = NULL;
+	if (output->current_wl_buffer != NULL) {
+		wl_buffer_destroy(output->current_wl_buffer);
+		output->current_wl_buffer = NULL;
+	}
+
+	assert(wlr_output->pending.committed & WLR_OUTPUT_STATE_BUFFER);
+	switch (wlr_output->pending.buffer_type) {
+	case WLR_OUTPUT_STATE_BUFFER_RENDER:
+		if (!wlr_egl_swap_buffers(&output->backend->egl,
+				output->egl_surface, damage)) {
+			return false;
+		}
+		break;
+	case WLR_OUTPUT_STATE_BUFFER_SCANOUT:
+		if (damage == NULL) {
+			wl_surface_damage_buffer(output->surface,
+				0, 0, INT32_MAX, INT32_MAX);
+		} else {
+			int rects_len;
+			pixman_box32_t *rects =
+				pixman_region32_rectangles(damage, &rects_len);
+			for (int i = 0; i < rects_len; i++) {
+				pixman_box32_t *r = &rects[i];
+				wl_surface_damage_buffer(output->surface, r->x1, r->y1,
+					r->x2 - r->x1, r->y2 - r->y1);
+			}
+		}
+		wl_surface_commit(output->surface);
+
+		output->current_buffer = wlr_buffer_ref(wlr_output->pending.buffer);
+		output->current_wl_buffer = output->pending_wl_buffer;
+		output->pending_wl_buffer = NULL;
+		break;
 	}
 
 	// TODO: if available, use the presentation-time protocol
 	wlr_output_send_present(wlr_output, NULL);
+
 	return true;
 }
 
@@ -222,6 +309,7 @@ static const struct wlr_output_impl output_impl = {
 	.set_custom_mode = output_set_custom_mode,
 	.destroy = output_destroy,
 	.attach_render = output_attach_render,
+	.attach_buffer  = output_attach_buffer,
 	.commit = output_commit,
 	.set_cursor = output_set_cursor,
 	.move_cursor = output_move_cursor,

include/backend/wayland.h

@@ -12,6 +12,7 @@
 #include <wlr/render/egl.h>
 #include <wlr/render/wlr_renderer.h>
 #include <wlr/types/wlr_box.h>
+#include <wlr/render/drm_format_set.h>
 
 struct wlr_wl_backend {
 	struct wlr_backend backend;
@@ -34,12 +35,14 @@ struct wlr_wl_backend {
 	struct xdg_wm_base *xdg_wm_base;
 	struct zxdg_decoration_manager_v1 *zxdg_decoration_manager_v1;
 	struct zwp_pointer_gestures_v1 *zwp_pointer_gestures_v1;
+	struct zwp_linux_dmabuf_v1 *zwp_linux_dmabuf_v1;
 	struct wl_seat *seat;
 	struct wl_pointer *pointer;
 	struct wl_keyboard *keyboard;
 	struct wlr_wl_pointer *current_pointer;
 	struct zwp_tablet_manager_v2 *tablet_manager;
 	char *seat_name;
+	struct wlr_drm_format_set linux_dmabuf_v1_formats;
 };
 
 struct wlr_wl_output {
@@ -55,6 +58,8 @@ struct wlr_wl_output {
 	struct zxdg_toplevel_decoration_v1 *zxdg_toplevel_decoration_v1;
 	struct wl_egl_window *egl_window;
 	EGLSurface egl_surface;
+	struct wl_buffer *pending_wl_buffer, *current_wl_buffer;
+	struct wlr_buffer *current_buffer;
 
 	uint32_t enter_serial;
 

protocol/meson.build

@@ -43,6 +43,7 @@ protocols = [
 client_protocols = [
 	[wl_protocol_dir, 'stable/xdg-shell/xdg-shell.xml'],
 	[wl_protocol_dir, 'unstable/idle-inhibit/idle-inhibit-unstable-v1.xml'],
+	[wl_protocol_dir, 'unstable/linux-dmabuf/linux-dmabuf-unstable-v1.xml'],
 	[wl_protocol_dir, 'unstable/pointer-constraints/pointer-constraints-unstable-v1.xml'],
 	[wl_protocol_dir, 'unstable/pointer-gestures/pointer-gestures-unstable-v1.xml'],
 	[wl_protocol_dir, 'unstable/relative-pointer/relative-pointer-unstable-v1.xml'],