Merge pull request #49 from ascent12/drm-atomic

Atomic modesetting

11 files changed, 350 insertions, 72 deletions

diff --git a/backend/drm/backend.c b/backend/drm/backend.c
index 68eae890..76aef9b9 100644
--- a/backend/drm/backend.c
+++ b/backend/drm/backend.c
@@ -53,7 +53,11 @@ static void session_signal(struct wl_listener *listener, void *data) {
 		for (size_t i = 0; i < drm->outputs->length; ++i) {
 			struct wlr_output_state *output = drm->outputs->items[i];
 			wlr_drm_output_start_renderer(output);
-			wlr_drm_crtc_set_cursor(drm, output->crtc);
+
+			struct wlr_drm_plane *plane = output->crtc->cursor;
+
+			drm->iface->crtc_set_cursor(drm, output->crtc,
+				plane ? plane->cursor_bo : NULL);
 		}
 	} else {
 		wlr_log(L_INFO, "DRM fd paused");
diff --git a/backend/drm/drm-atomic.c b/backend/drm/drm-atomic.c
new file mode 100644
index 00000000..0b8a7b1d
--- /dev/null
+++ b/backend/drm/drm-atomic.c
@@ -0,0 +1,176 @@
+#include <gbm.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+#include <wlr/util/log.h>
+#include "backend/drm.h"
+#include "backend/drm-util.h"
+
+struct atomic {
+	drmModeAtomicReq *req;
+	int cursor;
+	bool failed;
+};
+
+static void atomic_begin(struct wlr_drm_crtc *crtc, struct atomic *atom) {
+	if (!crtc->atomic) {
+		crtc->atomic = drmModeAtomicAlloc();
+		if (!crtc->atomic) {
+			wlr_log_errno(L_ERROR, "Allocation failed");
+			atom->failed = true;
+			return;
+		}
+	}
+
+	atom->req = crtc->atomic;
+	atom->cursor = drmModeAtomicGetCursor(atom->req);
+	atom->failed = false;
+}
+
+static bool atomic_end(int drm_fd, struct atomic *atom) {
+	if (atom->failed) {
+		return false;
+	}
+
+	uint32_t flags = DRM_MODE_ATOMIC_TEST_ONLY | DRM_MODE_ATOMIC_NONBLOCK;
+
+	if (drmModeAtomicCommit(drm_fd, atom->req, flags, NULL)) {
+		wlr_log_errno(L_ERROR, "Atomic test failed");
+		drmModeAtomicSetCursor(atom->req, atom->cursor);
+		return false;
+	}
+
+	return true;
+}
+
+static bool atomic_commit(int drm_fd, struct atomic *atom, struct wlr_output_state *output,
+		uint32_t flag) {
+	if (atom->failed) {
+		return false;
+	}
+
+	uint32_t flags = DRM_MODE_PAGE_FLIP_EVENT | DRM_MODE_ATOMIC_NONBLOCK | flag;
+
+	int ret = drmModeAtomicCommit(drm_fd, atom->req, flags, output);
+	if (ret) {
+		wlr_log_errno(L_ERROR, "Atomic commit failed");
+	}
+
+	drmModeAtomicSetCursor(atom->req, 0);
+
+	return !ret;
+}
+
+static inline void atomic_add(struct atomic *atom, uint32_t id, uint32_t prop, uint64_t val) {
+	if (!atom->failed && drmModeAtomicAddProperty(atom->req, id, prop, val) < 0) {
+		wlr_log_errno(L_ERROR, "Failed to add atomic DRM property");
+		atom->failed = true;
+	}
+}
+
+static void set_plane_props(struct atomic *atom, struct wlr_drm_plane *plane,
+		uint32_t crtc_id, uint32_t fb_id, bool set_crtc_xy) {
+	uint32_t id = plane->id;
+	const union wlr_drm_plane_props *props = &plane->props;
+
+	// The src_* properties are in 16.16 fixed point
+	atomic_add(atom, id, props->src_x, 0);
+	atomic_add(atom, id, props->src_y, 0);
+	atomic_add(atom, id, props->src_w, plane->width << 16);
+	atomic_add(atom, id, props->src_h, plane->height << 16);
+	atomic_add(atom, id, props->crtc_w, plane->width);
+	atomic_add(atom, id, props->crtc_h, plane->height);
+	atomic_add(atom, id, props->fb_id, fb_id);
+	atomic_add(atom, id, props->crtc_id, crtc_id);
+	if (set_crtc_xy) {
+		atomic_add(atom, id, props->crtc_x, 0);
+		atomic_add(atom, id, props->crtc_y, 0);
+	}
+}
+
+static bool atomic_crtc_pageflip(struct wlr_backend_state *drm, struct wlr_output_state *output,
+		struct wlr_drm_crtc *crtc, uint32_t fb_id, drmModeModeInfo *mode) {
+	if (mode) {
+		if (crtc->mode_id) {
+			drmModeDestroyPropertyBlob(drm->fd, crtc->mode_id);
+		}
+
+		if (drmModeCreatePropertyBlob(drm->fd, mode, sizeof(*mode), &crtc->mode_id)) {
+			wlr_log_errno(L_ERROR, "Unable to create property blob");
+			return false;
+		}
+	}
+
+	struct atomic atom;
+
+	atomic_begin(crtc, &atom);
+	atomic_add(&atom, output->connector, output->props.crtc_id, crtc->id);
+	atomic_add(&atom, crtc->id, crtc->props.mode_id, crtc->mode_id);
+	atomic_add(&atom, crtc->id, crtc->props.active, 1);
+	set_plane_props(&atom, crtc->primary, crtc->id, fb_id, true);
+	return atomic_commit(drm->fd, &atom, output, mode ? DRM_MODE_ATOMIC_ALLOW_MODESET : 0);
+}
+
+static void atomic_conn_enable(struct wlr_backend_state *drm, struct wlr_output_state *output,
+		bool enable) {
+	struct wlr_drm_crtc *crtc = output->crtc;
+	struct atomic atom;
+
+	atomic_begin(crtc, &atom);
+	atomic_add(&atom, crtc->id, crtc->props.active, enable);
+	atomic_end(drm->fd, &atom);
+}
+
+bool legacy_crtc_set_cursor(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc,
+	struct gbm_bo *bo);
+
+static bool atomic_crtc_set_cursor(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc,
+		struct gbm_bo *bo) {
+	if (!crtc || !crtc->cursor) {
+		return true;
+	}
+
+	struct wlr_drm_plane *plane = crtc->cursor;
+	// We can't use atomic operations on fake planes
+	if (plane->id == 0) {
+		return legacy_crtc_set_cursor(drm, crtc, bo);
+	}
+
+	struct atomic atom;
+
+	atomic_begin(crtc, &atom);
+
+	if (bo) {
+		set_plane_props(&atom, plane, crtc->id, get_fb_for_bo(bo), false);
+	} else {
+		atomic_add(&atom, plane->id, plane->props.fb_id, 0);
+		atomic_add(&atom, plane->id, plane->props.crtc_id, 0);
+	}
+
+	return atomic_end(drm->fd, &atom);
+}
+
+bool legacy_crtc_move_cursor(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc,
+	int x, int y);
+
+static bool atomic_crtc_move_cursor(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc,
+		int x, int y) {
+	struct wlr_drm_plane *plane = crtc->cursor;
+	// We can't use atomic operations on fake planes
+	if (plane->id == 0) {
+		return legacy_crtc_move_cursor(drm, crtc, x, y);
+	}
+
+	struct atomic atom;
+
+	atomic_begin(crtc, &atom);
+	atomic_add(&atom, plane->id, plane->props.crtc_x, x);
+	atomic_add(&atom, plane->id, plane->props.crtc_y, y);
+	return atomic_end(drm->fd, &atom);
+}
+
+const struct wlr_drm_interface atomic_iface = {
+	.conn_enable = atomic_conn_enable,
+	.crtc_pageflip = atomic_crtc_pageflip,
+	.crtc_set_cursor = atomic_crtc_set_cursor,
+	.crtc_move_cursor = atomic_crtc_move_cursor,
+};
diff --git a/backend/drm/drm-legacy.c b/backend/drm/drm-legacy.c
new file mode 100644
index 00000000..f7adac86
--- /dev/null
+++ b/backend/drm/drm-legacy.c
@@ -0,0 +1,58 @@
+#include <gbm.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+#include <wlr/util/log.h>
+#include "backend/drm.h"
+#include "backend/drm-util.h"
+
+static bool legacy_crtc_pageflip(struct wlr_backend_state *drm, struct wlr_output_state *output,
+		struct wlr_drm_crtc *crtc, uint32_t fb_id, drmModeModeInfo *mode) {
+	if (mode) {
+		drmModeSetCrtc(drm->fd, crtc->id, fb_id, 0, 0,
+			&output->connector, 1, mode);
+	}
+
+	drmModePageFlip(drm->fd, crtc->id, fb_id, DRM_MODE_PAGE_FLIP_EVENT, output);
+
+	return true;
+}
+
+static void legacy_conn_enable(struct wlr_backend_state *drm, struct wlr_output_state *output,
+		bool enable) {
+	drmModeConnectorSetProperty(drm->fd, output->connector, output->props.dpms,
+		enable ? DRM_MODE_DPMS_ON : DRM_MODE_DPMS_OFF);
+}
+
+bool legacy_crtc_set_cursor(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc,
+		struct gbm_bo *bo) {
+	if (!crtc || !crtc->cursor) {
+		return true;
+	}
+
+	if (!bo) {
+		drmModeSetCursor(drm->fd, crtc->id, 0, 0, 0);
+		return true;
+	}
+
+	struct wlr_drm_plane *plane = crtc->cursor;
+
+	if (drmModeSetCursor(drm->fd, crtc->id, gbm_bo_get_handle(bo).u32,
+			plane->width, plane->height)) {
+		wlr_log_errno(L_ERROR, "Failed to set hardware cursor");
+		return false;
+	}
+
+	return true;
+}
+
+bool legacy_crtc_move_cursor(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc,
+		int x, int y) {
+	return !drmModeMoveCursor(drm->fd, crtc->id, x, y);
+}
+
+const struct wlr_drm_interface legacy_iface = {
+	.conn_enable = legacy_conn_enable,
+	.crtc_pageflip = legacy_crtc_pageflip,
+	.crtc_set_cursor = legacy_crtc_set_cursor,
+	.crtc_move_cursor = legacy_crtc_move_cursor,
+};
diff --git a/backend/drm/drm-properties.c b/backend/drm/drm-properties.c
index 1b6e745f..ef24476f 100644
--- a/backend/drm/drm-properties.c
+++ b/backend/drm/drm-properties.c
@@ -27,6 +27,8 @@ static const struct prop_info connector_info[] = {
 
 static const struct prop_info crtc_info[] = {
 #define INDEX(name) (offsetof(union wlr_drm_crtc_props, name) / sizeof(uint32_t))
+	{ "ACTIVE",       INDEX(active) },
+	{ "MODE_ID",      INDEX(mode_id) },
 	{ "rotation",     INDEX(rotation) },
 	{ "scaling mode", INDEX(scaling_mode) },
 #undef INDEX
diff --git a/backend/drm/drm-util.c b/backend/drm/drm-util.c
index 6159b5de..0f8ee18c 100644
--- a/backend/drm/drm-util.c
+++ b/backend/drm/drm-util.c
@@ -2,7 +2,9 @@
 #include <string.h>
 #include <drm.h>
 #include <drm_mode.h>
+#include <gbm.h>
 #include "backend/drm-util.h"
+#include <wlr/util/log.h>
 
 int32_t calculate_refresh_rate(drmModeModeInfo *mode) {
 	int32_t refresh = (mode->clock * 1000000LL / mode->htotal +
@@ -133,6 +135,40 @@ const char *conn_get_name(uint32_t type_id) {
 	}
 }
 
+static void free_fb(struct gbm_bo *bo, void *data) {
+	uint32_t id = (uintptr_t)data;
+
+	if (id) {
+		struct gbm_device *gbm = gbm_bo_get_device(bo);
+		drmModeRmFB(gbm_device_get_fd(gbm), id);
+	}
+}
+
+uint32_t get_fb_for_bo(struct gbm_bo *bo) {
+	uint32_t id = (uintptr_t)gbm_bo_get_user_data(bo);
+	if (id) {
+		return id;
+	}
+
+	struct gbm_device *gbm = gbm_bo_get_device(bo);
+
+	int fd = gbm_device_get_fd(gbm);
+	uint32_t width = gbm_bo_get_width(bo);
+	uint32_t height = gbm_bo_get_height(bo);
+	uint32_t handles[4] = {gbm_bo_get_handle(bo).u32};
+	uint32_t pitches[4] = {gbm_bo_get_stride(bo)};
+	uint32_t offsets[4] = {gbm_bo_get_offset(bo, 0)};
+	uint32_t format = gbm_bo_get_format(bo);
+
+	if (drmModeAddFB2(fd, width, height, format, handles, pitches, offsets, &id, 0)) {
+		wlr_log_errno(L_ERROR, "Unable to add DRM framebuffer");
+	}
+
+	gbm_bo_set_user_data(bo, (void *)(uintptr_t)id, free_fb);
+
+	return id;
+}
+
 static inline bool is_taken(size_t n, const uint32_t arr[static n], uint32_t key) {
 	for (size_t i = 0; i < n; ++i) {
 		if (arr[i] == key) {
diff --git a/backend/drm/drm.c b/backend/drm/drm.c
index c4834081..1c83af3e 100644
--- a/backend/drm/drm.c
+++ b/backend/drm/drm.c
@@ -23,28 +23,33 @@
 #include "backend/drm-util.h"
 
 bool wlr_drm_check_features(struct wlr_backend_state *drm) {
+	extern const struct wlr_drm_interface legacy_iface;
+	extern const struct wlr_drm_interface atomic_iface;
+
 	if (drmSetClientCap(drm->fd, DRM_CLIENT_CAP_UNIVERSAL_PLANES, 1)) {
-		wlr_log(L_INFO, "DRM universal planes unsupported");
+		wlr_log(L_ERROR, "DRM universal planes unsupported");
 		return false;
 	}
 
 	if (drmSetClientCap(drm->fd, DRM_CLIENT_CAP_ATOMIC, 1)) {
-		wlr_log(L_INFO, "Atomic modesetting unsupported");
+		wlr_log(L_DEBUG, "Atomic modesetting unsupported, using legacy DRM interface");
+		drm->iface = &legacy_iface;
+	} else {
+		wlr_log(L_DEBUG, "Using atomic DRM interface");
+		drm->iface = &atomic_iface;
 	}
 
 	return true;
 }
 
-static int cmp_plane(const void *arg1, const void *arg2)
-{
+static int cmp_plane(const void *arg1, const void *arg2) {
 	const struct wlr_drm_plane *a = arg1;
 	const struct wlr_drm_plane *b = arg2;
 
 	return (int)a->type - (int)b->type;
 }
 
-static bool init_planes(struct wlr_backend_state *drm)
-{
+static bool init_planes(struct wlr_backend_state *drm) {
 	drmModePlaneRes *plane_res = drmModeGetPlaneResources(drm->fd);
 	if (!plane_res) {
 		wlr_log_errno(L_ERROR, "Failed to get DRM plane resources");
@@ -150,6 +155,15 @@ void wlr_drm_resources_free(struct wlr_backend_state *drm) {
 		return;
 	}
 
+	for (size_t i = 0; i < drm->num_crtcs; ++i) {
+		struct wlr_drm_crtc *crtc = &drm->crtcs[i];
+
+		drmModeAtomicFree(crtc->atomic);
+		if (crtc->mode_id) {
+			drmModeDestroyPropertyBlob(drm->fd, crtc->mode_id);
+		}
+	}
+
 	free(drm->crtcs);
 	free(drm->planes);
 }
@@ -180,7 +194,7 @@ void wlr_drm_renderer_free(struct wlr_drm_renderer *renderer) {
 }
 
 static bool wlr_drm_plane_renderer_init(struct wlr_drm_renderer *renderer,
-		struct wlr_drm_plane *plane, uint32_t width, uint32_t height, uint32_t flags) {
+		struct wlr_drm_plane *plane, uint32_t width, uint32_t height, uint32_t format, uint32_t flags) {
 	if (plane->width == width && plane->height == height) {
 		return true;
 	}
@@ -189,7 +203,7 @@ static bool wlr_drm_plane_renderer_init(struct wlr_drm_renderer *renderer,
 	plane->height = height;
 
 	plane->gbm = gbm_surface_create(renderer->gbm, width, height,
-		GBM_FORMAT_ARGB8888, GBM_BO_USE_RENDERING | flags);
+		format, GBM_BO_USE_RENDERING | flags);
 	if (!plane->gbm) {
 		wlr_log_errno(L_ERROR, "Failed to create GBM surface for plane");
 		return false;
@@ -210,6 +224,8 @@ static void wlr_drm_plane_renderer_free(struct wlr_drm_renderer *renderer,
 		return;
 	}
 
+	eglMakeCurrent(renderer->egl.display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
+
 	if (plane->front) {
 		gbm_surface_release_buffer(plane->gbm, plane->front);
 	}
@@ -245,30 +261,6 @@ static void wlr_drm_plane_renderer_free(struct wlr_drm_renderer *renderer,
 	plane->cursor_bo = NULL;
 }
 
-static void free_fb(struct gbm_bo *bo, void *data) {
-	uint32_t id = (uintptr_t)data;
-
-	if (id) {
-		struct gbm_device *gbm = gbm_bo_get_device(bo);
-		drmModeRmFB(gbm_device_get_fd(gbm), id);
-	}
-}
-
-static uint32_t get_fb_for_bo(struct gbm_bo *bo) {
-	uint32_t id = (uintptr_t)gbm_bo_get_user_data(bo);
-	if (id) {
-		return id;
-	}
-
-	struct gbm_device *gbm = gbm_bo_get_device(bo);
-	drmModeAddFB(gbm_device_get_fd(gbm), gbm_bo_get_width(bo), gbm_bo_get_height(bo),
-		24, 32, gbm_bo_get_stride(bo), gbm_bo_get_handle(bo).u32, &id);
-
-	gbm_bo_set_user_data(bo, (void *)(uintptr_t)id, free_fb);
-
-	return id;
-}
-
 static void wlr_drm_plane_make_current(struct wlr_drm_renderer *renderer,
 		struct wlr_drm_plane *plane) {
 	eglMakeCurrent(renderer->egl.display, plane->egl, plane->egl,
@@ -292,14 +284,14 @@ static void wlr_drm_output_make_current(struct wlr_output_state *output) {
 }
 
 static void wlr_drm_output_swap_buffers(struct wlr_output_state *output) {
+	struct wlr_backend_state *drm = wl_container_of(output->renderer, drm, renderer);
 	struct wlr_drm_renderer *renderer = output->renderer;
 	struct wlr_drm_crtc *crtc = output->crtc;
 	struct wlr_drm_plane *plane = crtc->primary;
 
 	wlr_drm_plane_swap_buffers(renderer, plane);
-	uint32_t fb_id = get_fb_for_bo(plane->back);
 
-	drmModePageFlip(renderer->fd, crtc->id, fb_id, DRM_MODE_PAGE_FLIP_EVENT, output);
+	drm->iface->crtc_pageflip(drm, output, crtc, get_fb_for_bo(plane->back), NULL);
 	output->pageflip_pending = true;
 }
 
@@ -308,8 +300,8 @@ void wlr_drm_output_start_renderer(struct wlr_output_state *output) {
 		return;
 	}
 
+	struct wlr_backend_state *drm = wl_container_of(output->renderer, drm, renderer);
 	struct wlr_drm_renderer *renderer = output->renderer;
-	struct wlr_output_mode *mode = output->base->current_mode;
 	struct wlr_drm_crtc *crtc = output->crtc;
 	struct wlr_drm_plane *plane = crtc->primary;
 
@@ -325,28 +317,22 @@ void wlr_drm_output_start_renderer(struct wlr_output_state *output) {
 		bo = plane->back;
 	}
 
-	uint32_t fb_id = get_fb_for_bo(bo);
-	drmModeSetCrtc(renderer->fd, crtc->id, fb_id, 0, 0,
-		&output->connector, 1, &mode->state->mode);
-	drmModePageFlip(renderer->fd, crtc->id, fb_id, DRM_MODE_PAGE_FLIP_EVENT, output);
+	drmModeModeInfo *mode = &output->base->current_mode->state->mode;
+	drm->iface->crtc_pageflip(drm, output, crtc, get_fb_for_bo(bo), mode);
 	output->pageflip_pending = true;
 }
 
 static void wlr_drm_output_enable(struct wlr_output_state *output, bool enable) {
-	struct wlr_backend_state *state =
-		wl_container_of(output->renderer, state, renderer);
+	struct wlr_backend_state *drm =
+		wl_container_of(output->renderer, drm, renderer);
 	if (output->state != WLR_DRM_OUTPUT_CONNECTED) {
 		return;
 	}
 
-	if (enable) {
-		drmModeConnectorSetProperty(state->fd, output->connector, output->props.dpms,
-			DRM_MODE_DPMS_ON);
+	drm->iface->conn_enable(drm, output, enable);
 
+	if (enable) {
 		wlr_drm_output_start_renderer(output);
-	} else {
-		drmModeConnectorSetProperty(state->fd, output->connector, output->props.dpms,
-			DRM_MODE_DPMS_OFF);
 	}
 }
 
@@ -515,7 +501,8 @@ static bool wlr_drm_output_set_mode(struct wlr_output_state *output,
 		}
 
 		if (!wlr_drm_plane_renderer_init(&drm->renderer, crtc->primary,
-				mode->width, mode->height, GBM_BO_USE_SCANOUT)) {
+				mode->width, mode->height, GBM_FORMAT_XRGB8888,
+				GBM_BO_USE_SCANOUT)) {
 			wlr_log(L_ERROR, "Failed to initalise renderer for plane");
 			goto error_enc;
 		}
@@ -541,22 +528,6 @@ static void wlr_drm_output_transform(struct wlr_output_state *output,
 	output->base->transform = transform;
 }
 
-bool wlr_drm_crtc_set_cursor(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc) {
-	if (!crtc || !crtc->cursor || !crtc->cursor->gbm) {
-		return true;
-	}
-
-	struct wlr_drm_plane *plane = crtc->cursor;
-
-	uint32_t bo_handle = gbm_bo_get_handle(plane->cursor_bo).u32;
-	if (drmModeSetCursor(drm->fd, crtc->id, bo_handle, plane->width, plane->height)) {
-		wlr_log_errno(L_ERROR, "Failed to set hardware cursor");
-		return false;
-	}
-
-	return true;
-}
-
 static bool wlr_drm_output_set_cursor(struct wlr_output_state *output,
 		const uint8_t *buf, int32_t stride, uint32_t width, uint32_t height) {
 	struct wlr_backend_state *drm = wl_container_of(output->renderer, drm, renderer);
@@ -565,10 +536,10 @@ static bool wlr_drm_output_set_cursor(struct wlr_output_state *output,
 	struct wlr_drm_plane *plane = crtc->cursor;
 
 	if (!buf) {
-		drmModeSetCursor(drm->fd, crtc->id, 0, 0, 0);
-		return true;
+		return drm->iface->crtc_set_cursor(drm, crtc, NULL);
 	}
 
+	// We don't have a real cursor plane, so we make a fake one
 	if (!plane) {
 		plane = calloc(1, sizeof(*plane));
 		if (!plane) {
@@ -591,7 +562,7 @@ static bool wlr_drm_output_set_cursor(struct wlr_output_state *output,
 			return false;
 		}
 
-		if (!wlr_drm_plane_renderer_init(renderer, plane, w, h, 0)) {
+		if (!wlr_drm_plane_renderer_init(renderer, plane, w, h, GBM_FORMAT_ARGB8888, 0)) {
 			wlr_log(L_ERROR, "Cannot allocate cursor resources");
 			return false;
 		}
@@ -653,14 +624,14 @@ static bool wlr_drm_output_set_cursor(struct wlr_output_state *output,
 
 	gbm_bo_unmap(bo, bo_data);
 
-	return wlr_drm_crtc_set_cursor(drm, crtc);
+	return drm->iface->crtc_set_cursor(drm, crtc, bo);
 }
 
 static bool wlr_drm_output_move_cursor(struct wlr_output_state *output,
 		int x, int y) {
 	struct wlr_backend_state *drm =
 		wl_container_of(output->renderer, drm, renderer);
-	return !drmModeMoveCursor(drm->fd, output->crtc->id, x, y);
+	return drm->iface->crtc_move_cursor(drm, output->crtc, x, y);
 }
 
 static void wlr_drm_output_destroy(struct wlr_output_state *output) {
diff --git a/backend/egl.c b/backend/egl.c
index 2ac1e77c..a547523c 100644
--- a/backend/egl.c
+++ b/backend/egl.c
@@ -162,6 +162,7 @@ error:
 }
 
 void wlr_egl_free(struct wlr_egl *egl) {
+	eglMakeCurrent(egl->display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
 	eglDestroyContext(egl->display, egl->context);
 	eglTerminate(egl->display);
 	eglReleaseThread();
diff --git a/backend/meson.build b/backend/meson.build
index a5bf5058..bb1b84c8 100644
--- a/backend/meson.build
+++ b/backend/meson.build
@@ -7,6 +7,8 @@ wlr_files += files(
     'session/session.c',
     'drm/backend.c',
     'drm/drm.c',
+    'drm/drm-atomic.c',
+    'drm/drm-legacy.c',
     'drm/drm-properties.c',
     'drm/drm-util.c',
     'libinput/backend.c',
diff --git a/include/backend/drm-properties.h b/include/backend/drm-properties.h
index 287fc1e0..7a061dd3 100644
--- a/include/backend/drm-properties.h
+++ b/include/backend/drm-properties.h
@@ -27,8 +27,13 @@ union wlr_drm_crtc_props {
 		// Neither of these are guranteed to exist
 		uint32_t rotation;
 		uint32_t scaling_mode;
+
+		// atomic-modesetting only
+
+		uint32_t active;
+		uint32_t mode_id;
 	};
-	uint32_t props[2];
+	uint32_t props[4];
 };
 
 union wlr_drm_plane_props {
diff --git a/include/backend/drm-util.h b/include/backend/drm-util.h
index 759bdb48..9abee6ea 100644
--- a/include/backend/drm-util.h
+++ b/include/backend/drm-util.h
@@ -12,6 +12,8 @@ int32_t calculate_refresh_rate(drmModeModeInfo *mode);
 void parse_edid(struct wlr_output *restrict output, size_t len, const uint8_t *data);
 // 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);
 
 // Part of match_obj
 enum {
diff --git a/include/backend/drm.h b/include/backend/drm.h
index aaa823f6..2f724524 100644
--- a/include/backend/drm.h
+++ b/include/backend/drm.h
@@ -43,6 +43,9 @@ struct wlr_drm_plane {
 
 struct wlr_drm_crtc {
 	uint32_t id;
+	uint32_t mode_id; // atomic modesetting only
+	drmModeAtomicReq *atomic;
+
 	union {
 		struct {
 			struct wlr_drm_plane *overlay;
@@ -76,8 +79,11 @@ struct wlr_drm_renderer {
 bool wlr_drm_renderer_init(struct wlr_drm_renderer *renderer, int fd);
 void wlr_drm_renderer_free(struct wlr_drm_renderer *renderer);
 
+struct wlr_drm_interface;
+
 struct wlr_backend_state {
 	struct wlr_backend *base;
+	const struct wlr_drm_interface *iface;
 
 	int fd;
 	dev_t dev;
@@ -150,6 +156,22 @@ struct wlr_output_state {
 	bool pageflip_pending;
 };
 
+// Used to provide atomic or legacy DRM functions
+struct wlr_drm_interface {
+	// Enable or disable DPMS for output
+	void (*conn_enable)(struct wlr_backend_state *drm, struct wlr_output_state *output,
+		bool enable);
+	// Pageflip on crtc. If mode is non-NULL perform a full modeset using it.
+	bool (*crtc_pageflip)(struct wlr_backend_state *drm, struct wlr_output_state *output,
+		struct wlr_drm_crtc *crtc, uint32_t fb_id, drmModeModeInfo *mode);
+	// Enable the cursor buffer on crtc. Set bo to NULL to disable
+	bool (*crtc_set_cursor)(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc,
+		struct gbm_bo *bo);
+	// Move the cursor on crtc
+	bool (*crtc_move_cursor)(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc,
+		int x, int y);
+};
+
 bool wlr_drm_check_features(struct wlr_backend_state *drm);
 bool wlr_drm_resources_init(struct wlr_backend_state *drm);
 void wlr_drm_resources_free(struct wlr_backend_state *drm);
@@ -159,6 +181,5 @@ void wlr_drm_scan_connectors(struct wlr_backend_state *state);
 int wlr_drm_event(int fd, uint32_t mask, void *data);
 
 void wlr_drm_output_start_renderer(struct wlr_output_state *output);
-bool wlr_drm_crtc_set_cursor(struct wlr_backend_state *drm, struct wlr_drm_crtc *crtc);
 
 #endif