diff --git a/lib_xua/lib_xua/src/core/buffer/ep/ep_buffer.xc b/lib_xua/lib_xua/src/core/buffer/ep/ep_buffer.xc
index 8cfbdbd..bcb0e27 100644
--- a/lib_xua/lib_xua/src/core/buffer/ep/ep_buffer.xc
+++ b/lib_xua/lib_xua/src/core/buffer/ep/ep_buffer.xc
@@ -737,8 +737,15 @@ void XUA_Buffer_Ep(
                     if(usb_speed != XUD_SPEED_HS)
                         feedbackMul = 8ULL;  /* TODO Use 4 instead of 8 to avoid windows LSB issues? */
 
-                    /* Number of MCLK ticks in this SOF period (E.g = 125 * 24.576 = 3072) */
-                    int count = (int) ((short)(u_tmp - lastClock));
+                    /* Number of MCLK ticks in this SOF period (E.g = 125 * 24.576 = 3072)
+                     * 改动原因：原 (short) 截断只能处理 MCLK 计数 < 32768 的情况。
+                     * UAC1 使用 FS USB（SOF 周期 1ms），1024x MCLK（49.152MHz）时
+                     * 每个 SOF 产生 49152 ticks > 32767，(short) 溢出为 -16384（负数），
+                     * 导致 feedback 计算错误，录音 IN endpoint 缓冲区管理失败，录音卡住。
+                     * 改为 (unsigned short) 后：49152 = 0xC000，truncate 后仍为 49152，
+                     * 同时保留对 16-bit 端口计时器回绕（wraparound）的正确处理。
+                     * UAC2 HS SOF（125µs）下最大 6144 ticks < 32768，两者等价，无副作用。 */
+                    int count = (int) ((unsigned short)(u_tmp - lastClock));
 
                     unsigned long long full_result = count * feedbackMul * sampleFreq;
 
@@ -1235,7 +1242,7 @@ void XUA_Buffer_Ep(
                             {
                                 if (btn_start_time == 0)
                                 {
-                                    UserReadHIDButtons(&g_hidData[1]);
+                                   // UserReadHIDButtons(&g_hidData[1]);
                                     btn_start_time = now;
                                     XUD_SetReady_In(ep_hid, g_hidData, HID_BUTTON_REPORT_BYTES);
                                 }
diff --git a/lib_xua/lib_xua/src/core/uac_hwresources.h b/lib_xua/lib_xua/src/core/uac_hwresources.h
index 08ff66d..dda3f67 100644
--- a/lib_xua/lib_xua/src/core/uac_hwresources.h
+++ b/lib_xua/lib_xua/src/core/uac_hwresources.h
@@ -8,8 +8,8 @@
 #define CLKBLK_SPDIF_TX    XS1_CLKBLK_1
 #define CLKBLK_SPDIF_RX    XS1_CLKBLK_1
 #define CLKBLK_MCLK        XS1_CLKBLK_2
-#define CLKBLK_FLASHLIB    XS1_CLKBLK_3   /* Clock block for use by flash lib */
+#define CLKBLK_FLASHLIB    XS1_CLKBLK_1   /* Clock block for use by flash lib */
 #define CLKBLK_ADAT_RX     XS1_CLKBLK_REF /* Use REF for ADAT_RX on x200/AI series */
-#define CLKBLK_I2S_BIT     XS1_CLKBLK_1
+#define CLKBLK_I2S_BIT     XS1_CLKBLK_3
 
 #endif /* _UAC_HWRESOURCES_H_ */