[client] wayland: use nominal refresh for frame demand

Use the current wl_output mode for the requested producer cadence.
Presentation feedback can follow a slower VRR cadence, feeding that low
update rate back into the IDD. Select the fastest nominal mode when a
window spans multiple outputs.

client/displayservers/Wayland/output.c

@@ -318,6 +318,7 @@ static void outputModeHandler(void * opaque, struct wl_output * wl_output, uint3
   struct WaylandOutput * node = opaque;
   node->modeWidth   = width;
   node->modeHeight  = height;
+  node->modeRefresh = refresh;
 }
 
 static void outputDoneHandler(void * opaque, struct wl_output * output)
@@ -483,3 +484,27 @@ struct WaylandScale waylandOutputGetScale(struct wl_output * output)
       return node->scale;
   return waylandScaleFromInt(0);
 }
+
+bool waylandOutputGetFramePeriod(uint64_t * period)
+{
+  uint64_t fastest = 0;
+  struct SurfaceOutput * surfaceOutput;
+  wl_list_for_each(surfaceOutput, &wlWm.surfaceOutputs, link)
+  {
+    const struct WaylandOutput * output =
+      outputFind(surfaceOutput->output);
+    if (!output || output->modeRefresh <= 0)
+      continue;
+
+    const uint64_t candidate =
+      1000000000000ULL / (uint64_t)output->modeRefresh;
+    if (!fastest || candidate < fastest)
+      fastest = candidate;
+  }
+
+  if (!fastest)
+    return false;
+
+  *period = fastest;
+  return true;
+}

client/displayservers/Wayland/presentation.c

@@ -73,6 +73,12 @@ static void presentationFeedbackPresented(void * opaque,
 
 bool waylandGetFramePeriod(uint64_t * period)
 {
+  /* Frame demand must use the output's nominal rate. Basing demand on the
+   * observed presentation interval can lock a VRR session at its current,
+   * slower cadence. */
+  if (waylandOutputGetFramePeriod(period))
+    return true;
+
   const uint64_t value = atomic_load(&wlWm.presentationPeriod);
   if (!value)
     return false;

client/displayservers/Wayland/wayland.h

@@ -78,6 +78,7 @@ struct WaylandOutput
   int32_t logicalHeight;
   int32_t modeWidth;
   int32_t modeHeight;
+  int32_t modeRefresh;
   bool    modeRotate;
   struct wl_output * output;
   struct zxdg_output_v1 * xdgOutput;
@@ -386,6 +387,7 @@ void waylandOutputFree(void);
 void waylandOutputBind(uint32_t name, uint32_t version);
 void waylandOutputTryUnbind(uint32_t name);
 struct WaylandScale waylandOutputGetScale(struct wl_output * output);
+bool waylandOutputGetFramePeriod(uint64_t * period);
 void waylandOutputColorMgmtInit(struct WaylandOutput * output);
 void waylandOutputColorMgmtInitAll(void);
 void waylandOutputUpdateHDRWhiteLevel(void);