From 308d5cf367c5ca41640cda085dd120737fc36be7 Mon Sep 17 00:00:00 2001
From: Philipp Zabel <p.zabel@pengutronix.de>
Date: Tue, 18 Apr 2023 13:57:33 +0200
Subject: [PATCH] backend-pipewire: enable multi-backend support

Insert the backend into the weston_compositor::backend_list instead
of setting weston_compositor::backend. The compositor uses this to
determine whether the backend is capable of being loaded simultaneously
with other backends.

To stay backwards compatible, the PipeWire backend can be loaded as
primary backend. It also supports being loaded as secondary backend.

Co-authored-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 libweston/backend-pipewire/pipewire.c | 66 +++++++++++++++++----------
 1 file changed, 41 insertions(+), 25 deletions(-)

diff --git a/libweston/backend-pipewire/pipewire.c b/libweston/backend-pipewire/pipewire.c
index cc338da5..f0142812 100644
--- a/libweston/backend-pipewire/pipewire.c
+++ b/libweston/backend-pipewire/pipewire.c
@@ -628,6 +628,8 @@ pipewire_destroy(struct weston_backend *base)
 	weston_log_scope_destroy(b->debug);
 	b->debug = NULL;
 
+	wl_list_remove(&b->base.link);
+
 	pw_loop_leave(b->loop);
 	pw_loop_destroy(b->loop);
 	wl_event_source_remove(b->loop_source);
@@ -996,7 +998,7 @@ pipewire_backend_create(struct weston_compositor *compositor,
 	backend->base.destroy = pipewire_destroy;
 	backend->base.create_output = pipewire_create_output;
 
-	compositor->backend = &backend->base;
+	wl_list_insert(&compositor->backend_list, &backend->base.link);
 
 	backend->formats_count = ARRAY_LENGTH(pipewire_formats);
 	backend->formats = pixel_format_get_array(pipewire_formats,
@@ -1005,31 +1007,33 @@ pipewire_backend_create(struct weston_compositor *compositor,
 	backend->base.supported_presentation_clocks =
 			WESTON_PRESENTATION_CLOCKS_SOFTWARE;
 
-	switch (config->renderer) {
-	case WESTON_RENDERER_AUTO:
-	case WESTON_RENDERER_PIXMAN:
-		ret = weston_compositor_init_renderer(compositor,
-						      WESTON_RENDERER_PIXMAN,
-						      NULL);
-		break;
-	case WESTON_RENDERER_GL: {
-		const struct gl_renderer_display_options options = {
-			.egl_platform = EGL_PLATFORM_SURFACELESS_MESA,
-			.formats = backend->formats,
-			.formats_count = backend->formats_count,
-		};
-		ret = weston_compositor_init_renderer(compositor,
-						      WESTON_RENDERER_GL,
-						      &options.base);
-		break;
-	}
-	default:
-		weston_log("Unsupported renderer requested\n");
-		goto err_compositor;
-	}
+	if (!compositor->renderer) {
+		switch (config->renderer) {
+		case WESTON_RENDERER_AUTO:
+		case WESTON_RENDERER_PIXMAN:
+			ret = weston_compositor_init_renderer(compositor,
+							      WESTON_RENDERER_PIXMAN,
+							      NULL);
+			break;
+		case WESTON_RENDERER_GL: {
+			const struct gl_renderer_display_options options = {
+				.egl_platform = EGL_PLATFORM_SURFACELESS_MESA,
+				.formats = backend->formats,
+				.formats_count = backend->formats_count,
+			};
+			ret = weston_compositor_init_renderer(compositor,
+							      WESTON_RENDERER_GL,
+							      &options.base);
+			break;
+		}
+		default:
+			weston_log("Unsupported renderer requested\n");
+			goto err_compositor;
+		}
 
-	if (ret < 0)
-		goto err_compositor;
+		if (ret < 0)
+			goto err_compositor;
+	}
 
 	compositor->capabilities |= WESTON_CAP_ARBITRARY_MODES;
 
@@ -1055,6 +1059,7 @@ pipewire_backend_create(struct weston_compositor *compositor,
 	return backend;
 
 err_compositor:
+	wl_list_remove(&backend->base.link);
 	free(backend);
 	return NULL;
 }
@@ -1082,6 +1087,17 @@ weston_backend_init(struct weston_compositor *compositor,
 		return -1;
 	}
 
+	if (compositor->renderer) {
+		switch (compositor->renderer->type) {
+		case WESTON_RENDERER_PIXMAN:
+		case WESTON_RENDERER_GL:
+			break;
+		default:
+			weston_log("Renderer not supported by PipeWire backend\n");
+			return -1;
+		}
+	}
+
 	config_init_to_defaults(&config);
 	memcpy(&config, config_base, config_base->struct_size);