feat: various power and thermal optimizations, fix Printers app regression

kernel/src/Drivers/USB/Xhci.cpp

@@ -49,6 +49,7 @@ namespace Drivers::USB::Xhci {
 
     // Hot-plug deferred work
     static volatile bool g_hotplugPending[MAX_PORTS] = {};
+    static volatile bool g_deferredWorkPending = false;
     static bool g_hotplugProcessing = false;
 
     // MMIO region pointers
@@ -302,6 +303,7 @@ namespace Drivers::USB::Xhci {
                     // Defer enumeration to ProcessDeferredWork (called from timer tick)
                     if (g_bootScanComplete && portId >= 1 && portId <= g_maxPorts) {
                         g_hotplugPending[portId - 1] = true;
+                        g_deferredWorkPending = true;
                     }
                     break;
                 }
@@ -723,15 +725,20 @@ namespace Drivers::USB::Xhci {
         return g_initialized;
     }
 
+    bool HasDeferredWork() {
+        return g_initialized && g_deferredWorkPending;
+    }
+
     // -------------------------------------------------------------------------
     // ProcessDeferredWork - handle hot-plug outside interrupt context
     // Called from timer tick (same pattern as E1000E::Poll)
     // -------------------------------------------------------------------------
 
     void ProcessDeferredWork() {
-        if (!g_initialized || !g_bootScanComplete) return;
+        if (!g_initialized || !g_bootScanComplete || !g_deferredWorkPending) return;
         if (g_hotplugProcessing) return;
         g_hotplugProcessing = true;
+        g_deferredWorkPending = false;
 
         for (uint32_t port = 0; port < g_maxPorts; port++) {
             if (!g_hotplugPending[port]) continue;