Multi-GPU DRM

backend/drm/backend.c

@@ -92,8 +92,9 @@ static void drm_invalidated(struct wl_listener *listener, void *data) {
 }
 
 struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
-		struct wlr_session *session, int gpu_fd) {
+		struct wlr_session *session, int gpu_fd, struct wlr_backend *parent) {
 	assert(display && session && gpu_fd >= 0);
+	assert(!parent || wlr_backend_is_drm(parent));
 
 	char *name = drmGetDeviceNameFromFd2(gpu_fd);
 	drmVersion *version = drmGetVersion(gpu_fd);
@@ -116,6 +117,7 @@ struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
 	}
 
 	drm->fd = gpu_fd;
+	drm->parent = (struct wlr_drm_backend *)parent;
 
 	drm->drm_invalidated.notify = drm_invalidated;
 	wlr_session_signal_add(session, gpu_fd, &drm->drm_invalidated);

backend/drm/drm.c

@@ -186,6 +186,10 @@ static void wlr_drm_connector_swap_buffers(struct wlr_output *output) {
 	struct wlr_drm_plane *plane = crtc->primary;
 
 	struct gbm_bo *bo = wlr_drm_surface_swap_buffers(&plane->surf);
+	if (drm->parent) {
+		bo = wlr_drm_surface_mgpu_copy(&plane->mgpu_surf, bo);
+	}
+
 	uint32_t fb_id = get_fb_for_bo(bo);
 
 	if (drm->iface->crtc_pageflip(drm, conn, crtc, fb_id, NULL)) {
@@ -217,7 +221,8 @@ void wlr_drm_connector_start_renderer(struct wlr_drm_connector *conn) {
 	struct wlr_drm_crtc *crtc = conn->crtc;
 	struct wlr_drm_plane *plane = crtc->primary;
 
-	struct gbm_bo *bo = wlr_drm_surface_get_front(&plane->surf);
+	struct gbm_bo *bo = wlr_drm_surface_get_front(
+		drm->parent ? &plane->mgpu_surf : &plane->surf);
 	uint32_t fb_id = get_fb_for_bo(bo);
 
 	struct wlr_drm_mode *mode = (struct wlr_drm_mode *)conn->output.current_mode;
@@ -393,7 +398,6 @@ static bool wlr_drm_connector_set_mode(struct wlr_output *output,
 	wlr_log(L_INFO, "Modesetting '%s' with '%ux%u@%u mHz'", conn->output.name,
 			mode->width, mode->height, mode->refresh);
 
-	wlr_log(L_DEBUG, "%p %p", conn, drm);
 	conn->possible_crtc = get_possible_crtcs(drm->fd, conn->id);
 	if (conn->possible_crtc == 0) {
 		goto error_conn;
@@ -430,9 +434,8 @@ static bool wlr_drm_connector_set_mode(struct wlr_output *output,
 			continue;
 		}
 
-		if (!wlr_drm_surface_init(&crtc->primary->surf, &drm->renderer,
-				mode->width, mode->height, GBM_FORMAT_XRGB8888,
-				GBM_BO_USE_SCANOUT)) {
+		if (!wlr_drm_plane_surfaces_init(crtc->primary, drm,
+				mode->width, mode->height, GBM_FORMAT_XRGB8888)) {
 			wlr_log(L_ERROR, "Failed to initalise renderer for plane");
 			goto error_conn;
 		}
@@ -782,10 +785,9 @@ static void page_flip_handler(int fd, unsigned seq,
 		return;
 	}
 
-	struct wlr_drm_plane *plane = conn->crtc->primary;
-	if (plane->surf.front) {
-		gbm_surface_release_buffer(plane->surf.gbm, plane->surf.front);
-		plane->surf.front = NULL;
+	wlr_drm_surface_post(&conn->crtc->primary->surf);
+	if (drm->parent) {
+		wlr_drm_surface_post(&conn->crtc->primary->mgpu_surf);
 	}
 
 	if (drm->session->active) {
@@ -855,6 +857,7 @@ void wlr_drm_connector_cleanup(struct wlr_drm_connector *conn) {
 		struct wlr_drm_crtc *crtc = conn->crtc;
 		for (int i = 0; i < 3; ++i) {
 			wlr_drm_surface_finish(&crtc->planes[i]->surf);
+			wlr_drm_surface_finish(&crtc->planes[i]->mgpu_surf);
 			if (crtc->planes[i] && crtc->planes[i]->id == 0) {
 				free(crtc->planes[i]);
 				crtc->planes[i] = NULL;

backend/drm/renderer.c

@@ -1,12 +1,18 @@
 #include <stdbool.h>
+#include <stdlib.h>
+#include <unistd.h>
 
 #include <gbm.h>
 #include <GLES2/gl2.h>
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
+#include <wayland-util.h>
 
 #include <wlr/egl.h>
 #include <wlr/util/log.h>
+#include <wlr/render/matrix.h>
+#include <wlr/render/gles2.h>
+#include <wlr/render.h>
 #include "backend/drm/drm.h"
 
 bool wlr_drm_renderer_init(struct wlr_drm_renderer *renderer, int fd) {
@@ -22,6 +28,9 @@ bool wlr_drm_renderer_init(struct wlr_drm_renderer *renderer, int fd) {
 		return false;
 	}
 
+	struct wlr_drm_backend *drm = wl_container_of(renderer, drm, renderer);
+	renderer->wlr_rend = wlr_gles2_renderer_create(&drm->backend);
+
 	renderer->fd = fd;
 	return true;
 }
@@ -121,3 +130,111 @@ struct gbm_bo *wlr_drm_surface_get_front(struct wlr_drm_surface *surf) {
 	glClear(GL_COLOR_BUFFER_BIT);
 	return wlr_drm_surface_swap_buffers(surf);
 }
+
+void wlr_drm_surface_post(struct wlr_drm_surface *surf) {
+	if (surf->front) {
+		gbm_surface_release_buffer(surf->gbm, surf->front);
+		surf->front = NULL;
+	}
+}
+
+struct tex {
+	struct wlr_egl *egl;
+	EGLImageKHR img;
+	struct wlr_texture *tex;
+};
+
+static void free_eglimage(struct gbm_bo *bo, void *data) {
+	struct tex *tex = data;
+
+	wlr_egl_destroy_image(tex->egl, tex->img);
+	wlr_texture_destroy(tex->tex);
+	free(tex);
+}
+
+static struct wlr_texture *get_tex_for_bo(struct wlr_drm_renderer *renderer, struct gbm_bo *bo) {
+	struct tex *tex = gbm_bo_get_user_data(bo);
+	if (tex) {
+		return tex->tex;
+	}
+
+	tex = malloc(sizeof(*tex));
+	if (!tex) {
+		wlr_log_errno(L_ERROR, "Allocation failed");
+		return NULL;
+	}
+
+	tex->egl = &renderer->egl;
+
+	int dmabuf_fd = gbm_bo_get_fd(bo);
+	uint32_t width = gbm_bo_get_width(bo);
+	uint32_t height = gbm_bo_get_height(bo);
+
+	EGLint attribs[] = {
+		EGL_WIDTH, width,
+		EGL_HEIGHT, height,
+		EGL_LINUX_DRM_FOURCC_EXT, gbm_bo_get_format(bo),
+		EGL_DMA_BUF_PLANE0_FD_EXT, dmabuf_fd,
+		EGL_DMA_BUF_PLANE0_OFFSET_EXT, gbm_bo_get_offset(bo, 0),
+		EGL_DMA_BUF_PLANE0_PITCH_EXT, gbm_bo_get_stride_for_plane(bo, 0),
+		EGL_IMAGE_PRESERVED_KHR, EGL_FALSE,
+		EGL_NONE,
+	};
+
+	tex->img = renderer->egl.eglCreateImageKHR(renderer->egl.display, EGL_NO_CONTEXT,
+		EGL_LINUX_DMA_BUF_EXT, NULL, attribs);
+	if (!tex->img) {
+		wlr_log(L_ERROR, "Failed to create EGL image: %s", egl_error());
+		abort();
+	}
+
+	tex->tex = wlr_render_texture_create(renderer->wlr_rend);
+	wlr_texture_upload_eglimage(tex->tex, tex->img, width, height);
+
+	gbm_bo_set_user_data(bo, tex, free_eglimage);
+
+	return tex->tex;
+}
+
+struct gbm_bo *wlr_drm_surface_mgpu_copy(struct wlr_drm_surface *dest, struct gbm_bo *src) {
+	wlr_drm_surface_make_current(dest);
+
+	struct wlr_texture *tex = get_tex_for_bo(dest->renderer, src);
+
+	static const float matrix[16] = {
+		[0] = 2.0f,
+		[3] = -1.0f,
+		[5] = 2.0f,
+		[7] = -1.0f,
+		[10] = 1.0f,
+		[15] = 1.0f,
+	};
+
+	glViewport(0, 0, dest->width, dest->height);
+	glClearColor(0.0, 0.0, 0.0, 1.0);
+	glClear(GL_COLOR_BUFFER_BIT);
+	wlr_render_with_matrix(dest->renderer->wlr_rend, tex, &matrix);
+
+	return wlr_drm_surface_swap_buffers(dest);
+}
+
+bool wlr_drm_plane_surfaces_init(struct wlr_drm_plane *plane, struct wlr_drm_backend *drm,
+		int32_t width, uint32_t height, uint32_t format) {
+	if (!drm->parent) {
+		return wlr_drm_surface_init(&plane->surf, &drm->renderer, width, height,
+			format, GBM_BO_USE_SCANOUT);
+	}
+
+	if (!wlr_drm_surface_init(&plane->surf, &drm->parent->renderer,
+			width, height, format, GBM_BO_USE_LINEAR)) {
+		return false;
+	}
+
+	if (!wlr_drm_surface_init(&plane->mgpu_surf, &drm->renderer,
+			width, height, format, GBM_BO_USE_SCANOUT)) {
+		wlr_drm_surface_finish(&plane->surf);
+		return false;
+	}
+
+	return true;
+}