backend/drm: implement get_cursor_formats and get_cursor_size

backend/drm/backend.c

@@ -1,5 +1,6 @@
 #include <assert.h>
 #include <errno.h>
+#include <drm_fourcc.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -238,6 +239,35 @@ struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
 		goto error_event;
 	}
 
+	if (drm->parent) {
+		// We'll perform a multi-GPU copy for all submitted buffers, we need
+		// to be able to texture from them
+		struct wlr_renderer *renderer = drm->renderer.wlr_rend;
+		const struct wlr_drm_format_set *texture_formats =
+			wlr_renderer_get_dmabuf_texture_formats(renderer);
+		if (texture_formats == NULL) {
+			wlr_log(WLR_ERROR, "Failed to query renderer texture formats");
+			goto error_event;
+		}
+
+		for (size_t i = 0; i < texture_formats->len; i++) {
+			const struct wlr_drm_format *fmt = texture_formats->formats[i];
+			if (fmt->len == 0) {
+				// Modifiers aren't supported. The implicit modifier changes
+				// from a GPU to the other, so we can only accept linear
+				// buffers
+				wlr_drm_format_set_add(&drm->mgpu_formats, fmt->format,
+					DRM_FORMAT_MOD_LINEAR);
+				continue;
+			}
+
+			for (size_t j = 0; j < fmt->len; j++) {
+				wlr_drm_format_set_add(&drm->mgpu_formats, fmt->format,
+					fmt->modifiers[j]);
+			}
+		}
+	}
+
 	drm->session_destroy.notify = handle_session_destroy;
 	wl_signal_add(&session->events.destroy, &drm->session_destroy);
 

backend/drm/drm.c

@@ -26,9 +26,17 @@
 #include "backend/drm/util.h"
 #include "render/pixel_format.h"
 #include "render/swapchain.h"
+#include "types/wlr_buffer.h"
 #include "util/signal.h"
 
 bool check_drm_features(struct wlr_drm_backend *drm) {
+	if (drmGetCap(drm->fd, DRM_CAP_CURSOR_WIDTH, &drm->cursor_width)) {
+		drm->cursor_width = 64;
+	}
+	if (drmGetCap(drm->fd, DRM_CAP_CURSOR_HEIGHT, &drm->cursor_height)) {
+		drm->cursor_height = 64;
+	}
+
 	uint64_t cap;
 	if (drmGetCap(drm->fd, DRM_CAP_PRIME, &cap) ||
 			!(cap & DRM_PRIME_CAP_IMPORT)) {
@@ -1004,6 +1012,32 @@ static void drm_connector_destroy_output(struct wlr_output *output) {
 	memset(&conn->output, 0, sizeof(struct wlr_output));
 }
 
+static const struct wlr_drm_format_set *drm_connector_get_cursor_formats(
+		struct wlr_output *output, uint32_t buffer_caps) {
+	if (!(buffer_caps & WLR_BUFFER_CAP_DMABUF)) {
+		return NULL;
+	}
+	struct wlr_drm_connector *conn = get_drm_connector_from_output(output);
+	if (!conn->crtc) {
+		return false;
+	}
+	struct wlr_drm_plane *plane = conn->crtc->cursor;
+	if (!plane) {
+		return false;
+	}
+	if (conn->backend->parent) {
+		return &conn->backend->mgpu_formats;
+	}
+	return &plane->formats;
+}
+
+static void drm_connector_get_cursor_size(struct wlr_output *output,
+		int *width, int *height) {
+	struct wlr_drm_backend *drm = get_drm_backend_from_backend(output->backend);
+	*width = (int)drm->cursor_width;
+	*height = (int)drm->cursor_height;
+}
+
 static const struct wlr_output_impl output_impl = {
 	.set_cursor = drm_connector_set_cursor,
 	.move_cursor = drm_connector_move_cursor,
@@ -1014,6 +1048,8 @@ static const struct wlr_output_impl output_impl = {
 	.rollback_render = drm_connector_rollback_render,
 	.get_gamma_size = drm_connector_get_gamma_size,
 	.export_dmabuf = drm_connector_export_dmabuf,
+	.get_cursor_formats = drm_connector_get_cursor_formats,
+	.get_cursor_size = drm_connector_get_cursor_size,
 };
 
 bool wlr_output_is_drm(struct wlr_output *output) {

include/backend/drm/drm.h

@@ -87,6 +87,10 @@ struct wlr_drm_backend {
 
 	struct wlr_drm_renderer renderer;
 	struct wlr_session *session;
+
+	uint64_t cursor_width, cursor_height;
+
+	struct wlr_drm_format_set mgpu_formats;
 };
 
 enum wlr_drm_connector_state {