Handle secondary GPU reset

On a multi-gpu setup, a reset of the secondary GPU was detected
but not properly handled. This fixes that by recreating the mgpu renderer.

backend/drm/drm.c

@@ -666,7 +666,7 @@ static bool drm_connector_state_update_primary_fb(struct wlr_drm_connector *conn
 			return false;
 		}
 
-		local_buf = drm_surface_blit(&plane->mgpu_surf, source_buf);
+		local_buf = drm_surface_blit(drm, &plane->mgpu_surf, source_buf);
 		if (local_buf == NULL) {
 			return false;
 		}
@@ -1048,7 +1048,7 @@ static bool drm_connector_set_cursor(struct wlr_output *output,
 				return false;
 			}
 
-			local_buf = drm_surface_blit(&plane->mgpu_surf, buffer);
+			local_buf = drm_surface_blit(drm, &plane->mgpu_surf, buffer);
 			if (local_buf == NULL) {
 				return false;
 			}

backend/drm/renderer.c

@@ -12,6 +12,20 @@
 #include "render/pixel_format.h"
 #include "render/wlr_renderer.h"
 
+static void handle_lost_mgpu_renderer(struct wlr_drm_backend *drm) {
+	wlr_log(WLR_DEBUG, "Handling lost renderer");
+	for (size_t i = 0; i < drm->num_planes; ++i) {
+		struct wlr_drm_plane *plane = &drm->planes[i];
+		finish_drm_surface(&plane->mgpu_surf);
+	}
+	finish_drm_renderer(&drm->mgpu_renderer);
+
+	if (!init_drm_renderer(drm, &drm->mgpu_renderer)) {
+		wlr_log(WLR_ERROR, "Failed to initialize renderer");
+		return;
+	}
+}
+
 bool init_drm_renderer(struct wlr_drm_backend *drm,
 		struct wlr_drm_renderer *renderer) {
 	renderer->wlr_rend = renderer_autocreate_with_drm_fd(drm->fd);
@@ -73,8 +87,8 @@ bool init_drm_surface(struct wlr_drm_surface *surf,
 	return true;
 }
 
-struct wlr_buffer *drm_surface_blit(struct wlr_drm_surface *surf,
-		struct wlr_buffer *buffer) {
+struct wlr_buffer *drm_surface_blit(struct wlr_drm_backend *drm,
+		struct wlr_drm_surface *surf, struct wlr_buffer *buffer) {
 	struct wlr_renderer *renderer = surf->renderer->wlr_rend;
 
 	if (surf->swapchain->width != buffer->width ||
@@ -118,6 +132,9 @@ error_dst:
 	wlr_buffer_unlock(dst);
 error_tex:
 	wlr_texture_destroy(tex);
+	if (renderer->lost) {
+		handle_lost_mgpu_renderer(drm);
+	}
 	return NULL;
 }
 

include/backend/drm/renderer.h

@@ -31,8 +31,8 @@ bool init_drm_surface(struct wlr_drm_surface *surf,
 	const struct wlr_drm_format *drm_format);
 void finish_drm_surface(struct wlr_drm_surface *surf);
 
-struct wlr_buffer *drm_surface_blit(struct wlr_drm_surface *surf,
-	struct wlr_buffer *buffer);
+struct wlr_buffer *drm_surface_blit(struct wlr_drm_backend *drm,
+	struct wlr_drm_surface *surf, struct wlr_buffer *buffer);
 
 bool drm_plane_pick_render_format(struct wlr_drm_plane *plane,
 	struct wlr_drm_format *fmt, struct wlr_drm_renderer *renderer);

include/wlr/render/wlr_renderer.h

@@ -29,6 +29,7 @@ struct wlr_renderer {
 	// Capabilities required for the buffer used as a render target (bitmask of
 	// enum wlr_buffer_cap)
 	uint32_t render_buffer_caps;
+	bool lost;
 
 	struct {
 		struct wl_signal destroy;

render/gles2/pass.c

@@ -255,6 +255,7 @@ struct wlr_gles2_render_pass *begin_gles2_buffer_pass(struct wlr_gles2_buffer *b
 		GLenum status = renderer->procs.glGetGraphicsResetStatusKHR();
 		if (status != GL_NO_ERROR) {
 			wlr_log(WLR_ERROR, "GPU reset (%s)", reset_status_str(status));
+			renderer->wlr_renderer.lost = true;
 			wl_signal_emit_mutable(&renderer->wlr_renderer.events.lost, NULL);
 			return NULL;
 		}

render/wlr_renderer.c

@@ -38,6 +38,7 @@ void wlr_renderer_init(struct wlr_renderer *renderer,
 	*renderer = (struct wlr_renderer){
 		.impl = impl,
 		.render_buffer_caps = render_buffer_caps,
+		.lost = false,
 	};
 
 	wl_signal_init(&renderer->events.destroy);