DisplayServer (Linux): wait for delayed Wayland output events

src/detection/displayserver/linux/wayland/global-output.c

@@ -25,6 +25,11 @@ static void waylandOutputScaleListener(void* data, [[maybe_unused]] struct wl_ou
     display->dpi = 96 * (uint32_t) scale;
 }
 
+static void waylandOutputDoneListener(void* data, [[maybe_unused]] struct wl_output* output) {
+    WaylandDisplay* display = data;
+    display->done = true;
+}
+
 static void waylandOutputGeometryListener(void* data,
     [[maybe_unused]] struct wl_output* output,
     [[maybe_unused]] int32_t x,
@@ -54,7 +59,7 @@ static void handleXdgLogicalSize(void* data, [[maybe_unused]] struct zxdg_output
 static void* outputListener[] = {
     waylandOutputGeometryListener,      // geometry
     waylandOutputModeListener,          // mode
-    stubListener,                       // done
+    waylandOutputDoneListener,          // done
     waylandOutputScaleListener,         // scale
     ffWaylandOutputNameListener,        // name
     ffWaylandOutputDescriptionListener, // description
@@ -122,6 +127,13 @@ const char* ffWaylandHandleGlobalOutput(WaylandData* wldata, struct wl_registry*
         wldata->ffwl_proxy_destroy(output);
         return "Failed to roundtrip wl_output";
     }
+    if (bindVersion >= WL_OUTPUT_DONE_SINCE_VERSION && !display.done) {
+        const char* error = ffWaylandWaitForDone(&display);
+        if (error) {
+            wldata->ffwl_proxy_destroy(output);
+            return error;
+        }
+    }
 
     if (wldata->zxdgOutputManager) {
         uint32_t bindVersion = min(version, ZXDG_OUTPUT_V1_DESCRIPTION_SINCE_VERSION);

src/detection/displayserver/linux/wayland/kde-output.c

@@ -147,11 +147,16 @@ static void waylandKdePriorityListener(void* data, [[maybe_unused]] struct kde_o
     display->primary = priority == 1;
 }
 
+static void waylandKdeDoneListener(void* data, [[maybe_unused]] struct kde_output_device_v2* kde_output_device_v2) {
+    WaylandDisplay* display = data;
+    display->done = true;
+}
+
 static struct kde_output_device_v2_listener outputListener = {
     .geometry = waylandKdeGeometryListener,
     .current_mode = waylandKdeCurrentModeListener,
     .mode = waylandKdeModeListener,
-    .done = (void*) stubListener,
+    .done = waylandKdeDoneListener,
     .scale = waylandKdeScaleListener,
     .edid = waylandKdeEdidListener,
     .enabled = waylandKdeEnabledListener,
@@ -211,6 +216,13 @@ static const char* waylandKdeHandleOutput(WaylandData* wldata, struct wl_proxy*
         wldata->ffwl_proxy_destroy(output);
         return "Failed to roundtrip kde_output_device_v2";
     }
+    if (!display.done) {
+        const char* error = ffWaylandWaitForDone(&display);
+        if (error) {
+            wldata->ffwl_proxy_destroy(output);
+            return error;
+        }
+    }
     // Destroy any mode proxies that were created during the listeners.
     // wl proxies created for modes are not automatically freed by destroying
     // the parent output proxy, so destroy them explicitly to avoid leaks.

src/detection/displayserver/linux/wayland/wayland.c

@@ -11,6 +11,7 @@
     #include <sys/socket.h>
 
     #include "common/properties.h"
+    #include "common/time.h"
 
     #include "wayland.h"
     #include "kde-output-device-v2-client-protocol.h"
@@ -217,6 +218,26 @@ uint32_t ffWaylandHandleRotation(WaylandDisplay* display) {
     return rotation;
 }
 
+const char* ffWaylandWaitForDone(WaylandDisplay* display) {
+    WaylandData* wldata = display->parent;
+    double deadline = ffTimeGetTick() + instance.config.general.processingTimeout;
+
+    // Some compositors emit the final output state asynchronously after the roundtrip callback (#2074)
+    while (!display->done) {
+        if (ffTimeGetTick() >= deadline) {
+            return "Timeout waiting for Wayland output information";
+        }
+        if (wldata->ffwl_display_roundtrip(wldata->display) < 0) {
+            return "Failed to roundtrip Wayland output information";
+        }
+        if (!display->done) {
+            ffTimeSleep(1);
+        }
+    }
+
+    return nullptr;
+}
+
 const char* ffdsConnectWayland(FFDisplayServerResult* result) {
     if (getenv("XDG_RUNTIME_DIR") == nullptr) {
         return "Wayland requires $XDG_RUNTIME_DIR being set";

src/detection/displayserver/linux/wayland/wayland.h

@@ -58,6 +58,7 @@ typedef struct WaylandDisplay {
     FFstrbuf serial;
     uint8_t bitDepth;
     bool primary;
+    bool done;
 } WaylandDisplay;
 
 inline static void stubListener(void* data, ...) {
@@ -79,6 +80,7 @@ void ffWaylandOutputNameListener(void* data, [[maybe_unused]] void* output, cons
 void ffWaylandOutputDescriptionListener(void* data, [[maybe_unused]] void* output, const char* description);
 // Modifies content of display. Don't call this function when calling ffdsAppendDisplay
 uint32_t ffWaylandHandleRotation(WaylandDisplay* display);
+const char* ffWaylandWaitForDone(WaylandDisplay* display);
 
 const char* ffWaylandHandleGlobalOutput(WaylandData* wldata, struct wl_registry* registry, uint32_t name, uint32_t version);
 const char* ffWaylandHandleKdeOutputRegistry(WaylandData* wldata, struct wl_registry* registry, uint32_t name, uint32_t version);