feat: further kernel power and power optimizations

kernel/src/Drivers/USB/HidKeyboard.cpp

@@ -377,4 +377,17 @@ namespace Drivers::USB::HidKeyboard {
         }
     }
 
+    uint64_t GetNextTickDeadline() {
+        if (g_RepeatKey == 0) {
+            return 0;
+        }
+
+        uint64_t firstRepeat = g_RepeatStartMs + TYPEMATIC_DELAY_MS;
+        if (g_LastRepeatMs == 0 || g_LastRepeatMs < firstRepeat) {
+            return firstRepeat;
+        }
+
+        return g_LastRepeatMs + TYPEMATIC_PERIOD_MS;
+    }
+
 }

kernel/src/Drivers/USB/HidKeyboard.hpp

@@ -18,4 +18,8 @@ namespace Drivers::USB::HidKeyboard {
     // Timer tick for typematic repeat (call from periodic timer, e.g. 1ms)
     void Tick();
 
+    // Earliest millisecond deadline when typematic repeat needs service again.
+    // Returns 0 when no repeat is pending.
+    uint64_t GetNextTickDeadline();
+
 };

kernel/src/Drivers/USB/Xhci.cpp

@@ -959,7 +959,7 @@ namespace Drivers::USB::Xhci {
 
         // Enable interrupter 0
         WriteRt(IR0_IMAN, IMAN_IE);
-        WriteRt(IR0_IMOD, 0);
+        WriteRt(IR0_IMOD, IMOD_INTERVAL_100US);
 
         // Start controller
         WriteOp(OP_USBCMD, USBCMD_RS | USBCMD_INTE | USBCMD_HSEE);
@@ -1269,7 +1269,7 @@ namespace Drivers::USB::Xhci {
         // Step 13: Enable interrupter 0
         // -----------------------------------------------------------------
         WriteRt(IR0_IMAN, IMAN_IE);
-        WriteRt(IR0_IMOD, 0); // No moderation
+        WriteRt(IR0_IMOD, IMOD_INTERVAL_100US);
 
         // -----------------------------------------------------------------
         // Step 14: Start controller

kernel/src/Drivers/USB/Xhci.hpp

@@ -110,6 +110,7 @@ namespace Drivers::USB::Xhci {
     // IMAN bits
     constexpr uint32_t IMAN_IP         = (1 << 0);   // Interrupt Pending
     constexpr uint32_t IMAN_IE         = (1 << 1);   // Interrupt Enable
+    constexpr uint32_t IMOD_INTERVAL_100US = 400;    // 100 us in 250 ns units
 
     // ---------------------------------------------------------------------------
     // TRB (Transfer Request Block) - 16 bytes