From 2d70bdfdcdb236ee3e466b1a24df494da43c8a68 Mon Sep 17 00:00:00 2001
From: Leandro Ribeiro <leandro.ribeiro@collabora.com>
Date: Tue, 14 Feb 2023 22:33:11 -0300
Subject: [PATCH] drm-backend: add support to output capture writeback source

With this change, we expose the DRM-backend writeback source through the
output capture interface, making it available to clients.

For now we'll always fail writeback screenshots requests, because we
still don't have the writeback screenshooter implementation on the
DRM-backend. We add that in the following commits.

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
---
 libweston/backend-drm/drm.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/libweston/backend-drm/drm.c b/libweston/backend-drm/drm.c
index 78725f5c..a3297f9b 100644
--- a/libweston/backend-drm/drm.c
+++ b/libweston/backend-drm/drm.c
@@ -444,6 +444,26 @@ drm_output_render(struct drm_output_state *state, pixman_region32_t *damage)
 	pixman_region32_fini(&scanout_damage);
 }
 
+static void
+drm_output_pick_writeback_capture_task(struct drm_output *output)
+{
+	struct weston_capture_task *ct;
+	const char *msg = "drm: writeback screenshot not supported yet";
+	int32_t width = output->base.current_mode->width;
+	int32_t height = output->base.current_mode->height;
+	uint32_t format = output->format->format;
+
+	ct = weston_output_pull_capture_task(&output->base,
+					     WESTON_OUTPUT_CAPTURE_SOURCE_WRITEBACK,
+					     width, height, pixel_format_get_info(format));
+	if (!ct)
+		return;
+
+	assert(output->device->atomic_modeset);
+
+	weston_capture_task_retire_failed(ct, msg);
+}
+
 static int
 drm_output_repaint(struct weston_output *output_base, pixman_region32_t *damage)
 {
@@ -482,6 +502,8 @@ drm_output_repaint(struct weston_output *output_base, pixman_region32_t *damage)
 	if (drm_output_ensure_hdr_output_metadata_blob(output) < 0)
 		goto err;
 
+	drm_output_pick_writeback_capture_task(output);
+
 	drm_output_render(state, damage);
 	scanout_state = drm_output_state_get_plane(state,
 						   output->scanout_plane);
@@ -792,6 +814,13 @@ drm_output_apply_mode(struct drm_output *output)
 		}
 	}
 
+	if (device->atomic_modeset && !output->base.disable_planes)
+		weston_output_update_capture_info(&output->base,
+						  WESTON_OUTPUT_CAPTURE_SOURCE_WRITEBACK,
+						  output->base.current_mode->width,
+						  output->base.current_mode->height,
+						  pixel_format_get_info(output->format->format));
+
 	return 0;
 }
 
@@ -1967,6 +1996,12 @@ drm_output_enable(struct weston_output *base)
 	output->base.switch_mode = drm_output_switch_mode;
 	output->base.set_gamma = drm_output_set_gamma;
 
+	if (device->atomic_modeset && !base->disable_planes)
+		weston_output_update_capture_info(base, WESTON_OUTPUT_CAPTURE_SOURCE_WRITEBACK,
+						  base->current_mode->width,
+						  base->current_mode->height,
+						  pixel_format_get_info(output->format->format));
+
 	weston_log("Output %s (crtc %d) video modes:\n",
 		   output->base.name, output->crtc->crtc_id);
 	drm_output_print_modes(output);