backend/headless: remove swapchain

Rely on wlr_output's generic swapchain support instead of creating our
own. The headless output now simply keeps a reference to the front buffer
and does nothing else.

backend/headless/backend.c

@@ -70,8 +70,6 @@ static void backend_destroy(struct wlr_backend *wlr_backend) {
 
 	wlr_backend_finish(wlr_backend);
 
-	free(backend->format);
-
 	close(backend->drm_fd);
 	free(backend);
 }
@@ -146,20 +144,6 @@ static bool backend_init(struct wlr_headless_backend *backend,
 		return false;
 	}
 
-	const struct wlr_drm_format_set *formats =
-		wlr_renderer_get_render_formats(renderer);
-	if (formats == NULL) {
-		wlr_log(WLR_ERROR, "Failed to get available DMA-BUF formats from renderer");
-		return false;
-	}
-	const struct wlr_drm_format *format =
-		wlr_drm_format_set_get(formats, DRM_FORMAT_XRGB8888);
-	if (format == NULL) {
-		wlr_log(WLR_ERROR, "Renderer doesn't support XRGB8888");
-		return false;
-	}
-	backend->format = wlr_drm_format_dup(format);
-
 	backend->display_destroy.notify = handle_display_destroy;
 	wl_display_add_destroy_listener(display, &backend->display_destroy);
 

backend/headless/output.c

@@ -4,10 +4,7 @@
 #include <wlr/interfaces/wlr_output.h>
 #include <wlr/render/wlr_renderer.h>
 #include <wlr/util/log.h>
-#include "backend/backend.h"
 #include "backend/headless.h"
-#include "render/swapchain.h"
-#include "render/wlr_renderer.h"
 #include "util/signal.h"
 
 static struct wlr_headless_output *headless_output_from_output(
@@ -20,47 +17,17 @@ static bool output_set_custom_mode(struct wlr_output *wlr_output, int32_t width,
 		int32_t height, int32_t refresh) {
 	struct wlr_headless_output *output =
 		headless_output_from_output(wlr_output);
-	struct wlr_allocator *allocator = backend_get_allocator(wlr_output->backend);
 
 	if (refresh <= 0) {
 		refresh = HEADLESS_DEFAULT_REFRESH;
 	}
 
-	wlr_swapchain_destroy(output->swapchain);
-	output->swapchain = wlr_swapchain_create(allocator,
-			width, height, output->backend->format);
-	if (!output->swapchain) {
-		wlr_output_destroy(wlr_output);
-		return false;
-	}
-
 	output->frame_delay = 1000000 / refresh;
 
 	wlr_output_update_custom_mode(&output->wlr_output, width, height, refresh);
 	return true;
 }
 
-static bool output_attach_render(struct wlr_output *wlr_output,
-		int *buffer_age) {
-	struct wlr_headless_output *output =
-		headless_output_from_output(wlr_output);
-	struct wlr_renderer *renderer = wlr_backend_get_renderer(wlr_output->backend);
-
-	wlr_buffer_unlock(output->back_buffer);
-	output->back_buffer = wlr_swapchain_acquire(output->swapchain, buffer_age);
-	if (!output->back_buffer) {
-		wlr_log(WLR_ERROR, "Failed to acquire swapchain buffer");
-		return false;
-	}
-
-	if (!wlr_renderer_bind_buffer(renderer, output->back_buffer)) {
-		wlr_log(WLR_ERROR, "Failed to bind buffer to renderer");
-		return false;
-	}
-
-	return true;
-}
-
 static bool output_test(struct wlr_output *wlr_output) {
 	if (wlr_output->pending.committed & WLR_OUTPUT_STATE_ENABLED) {
 		wlr_log(WLR_DEBUG, "Cannot disable a headless output");
@@ -77,7 +44,6 @@ static bool output_test(struct wlr_output *wlr_output) {
 static bool output_commit(struct wlr_output *wlr_output) {
 	struct wlr_headless_output *output =
 		headless_output_from_output(wlr_output);
-	struct wlr_renderer *renderer = wlr_backend_get_renderer(wlr_output->backend);
 
 	if (!output_test(wlr_output)) {
 		return false;
@@ -93,26 +59,11 @@ static bool output_commit(struct wlr_output *wlr_output) {
 	}
 
 	if (wlr_output->pending.committed & WLR_OUTPUT_STATE_BUFFER) {
-		struct wlr_buffer *buffer = NULL;
+		assert(wlr_output->pending.buffer_type ==
-		switch (wlr_output->pending.buffer_type) {
+			WLR_OUTPUT_STATE_BUFFER_SCANOUT);
-		case WLR_OUTPUT_STATE_BUFFER_RENDER:
-			assert(output->back_buffer != NULL);
-
-			wlr_renderer_bind_buffer(renderer, NULL);
-
-			buffer = output->back_buffer;
-			output->back_buffer = NULL;
-			break;
-		case WLR_OUTPUT_STATE_BUFFER_SCANOUT:
-			buffer = wlr_buffer_lock(wlr_output->pending.buffer);
-			break;
-		}
-		assert(buffer != NULL);
 
 		wlr_buffer_unlock(output->front_buffer);
-		output->front_buffer = buffer;
+		output->front_buffer = wlr_buffer_lock(wlr_output->pending.buffer);
-
-		wlr_swapchain_set_buffer_submitted(output->swapchain, buffer);
 
 		wlr_output_send_present(wlr_output, NULL);
 	}
@@ -120,17 +71,6 @@ static bool output_commit(struct wlr_output *wlr_output) {
 	return true;
 }
 
-static void output_rollback_render(struct wlr_output *wlr_output) {
-	struct wlr_headless_output *output =
-		headless_output_from_output(wlr_output);
-	struct wlr_renderer *renderer = wlr_backend_get_renderer(wlr_output->backend);
-
-	wlr_renderer_bind_buffer(renderer, NULL);
-
-	wlr_buffer_unlock(output->back_buffer);
-	output->back_buffer = NULL;
-}
-
 static bool output_export_dmabuf(struct wlr_output *wlr_output,
 		struct wlr_dmabuf_attributes *attribs) {
 	struct wlr_headless_output *output =
@@ -153,17 +93,13 @@ static void output_destroy(struct wlr_output *wlr_output) {
 		headless_output_from_output(wlr_output);
 	wl_list_remove(&output->link);
 	wl_event_source_remove(output->frame_timer);
-	wlr_swapchain_destroy(output->swapchain);
-	wlr_buffer_unlock(output->back_buffer);
 	wlr_buffer_unlock(output->front_buffer);
 	free(output);
 }
 
 static const struct wlr_output_impl output_impl = {
 	.destroy = output_destroy,
-	.attach_render = output_attach_render,
 	.commit = output_commit,
-	.rollback_render = output_rollback_render,
 	.export_dmabuf = output_export_dmabuf,
 };
 
@@ -182,7 +118,6 @@ struct wlr_output *wlr_headless_add_output(struct wlr_backend *wlr_backend,
 		unsigned int width, unsigned int height) {
 	struct wlr_headless_backend *backend =
 		headless_backend_from_backend(wlr_backend);
-	struct wlr_allocator *allocator = backend_get_allocator(wlr_backend);
 
 	struct wlr_headless_output *output =
 		calloc(1, sizeof(struct wlr_headless_output));
@@ -195,12 +130,6 @@ struct wlr_output *wlr_headless_add_output(struct wlr_backend *wlr_backend,
 		backend->display);
 	struct wlr_output *wlr_output = &output->wlr_output;
 
-	output->swapchain = wlr_swapchain_create(allocator,
-		width, height, backend->format);
-	if (!output->swapchain) {
-		goto error;
-	}
-
 	output_set_custom_mode(wlr_output, width, height, 0);
 	strncpy(wlr_output->make, "headless", sizeof(wlr_output->make));
 	strncpy(wlr_output->model, "headless", sizeof(wlr_output->model));
@@ -224,8 +153,4 @@ struct wlr_output *wlr_headless_add_output(struct wlr_backend *wlr_backend,
 	}
 
 	return wlr_output;
-
-error:
-	wlr_output_destroy(&output->wlr_output);
-	return NULL;
 }

include/backend/headless.h

@@ -9,7 +9,6 @@
 struct wlr_headless_backend {
 	struct wlr_backend backend;
 	int drm_fd;
-	struct wlr_drm_format *format;
 	struct wl_display *display;
 	struct wl_list outputs;
 	size_t last_output_num;
@@ -26,8 +25,7 @@ struct wlr_headless_output {
 	struct wlr_headless_backend *backend;
 	struct wl_list link;
 
-	struct wlr_swapchain *swapchain;
+	struct wlr_buffer *front_buffer;
-	struct wlr_buffer *back_buffer, *front_buffer;
 
 	struct wl_event_source *frame_timer;
 	int frame_delay; // ms