调试记录-Android12开机默认开启MTP模式

需求

RK平台的Android12系统在userdebug模式下，默认是开启adb模式，开机即可以连接PC进行adb调试，部分客户有需要把默认的adb模式改为MTP模式，开机后可以默认以文件传输的方式连接PC。

实现

可以直接在Android层的UsbDeviceManager里面设置MTP模式：
具体路径是：frameworks/base/services/usb/java/com/android/server/usb/UsbDeviceManager.java
相关补丁：

diff --git a/services/usb/java/com/android/server/usb/UsbDeviceManager.java b/services/usb/java/com/android/server/usb/UsbDeviceManager.java
index 9626cfb1adcc..d2d7f872d7b2 100644
--- a/services/usb/java/com/android/server/usb/UsbDeviceManager.java
+++ b/services/usb/java/com/android/server/usb/UsbDeviceManager.java
@@ -906,7 +906,8 @@ public class UsbDeviceManager implements ActivityTaskManagerInternal.ScreenObser
                                     && mScreenUnlockedFunctions != UsbManager.FUNCTION_NONE) {
                                 setScreenUnlockedFunctions();
                             } else {
-                                setEnabledFunctions(UsbManager.FUNCTION_NONE, false);
+                                //setEnabledFunctions(UsbManager.FUNCTION_NONE, false);
+                                setEnabledFunctions(UsbManager.FUNCTION_MTP, true);
                             }
                         }
                         updateUsbFunctions();
@@ -1118,7 +1119,8 @@ public class UsbDeviceManager implements ActivityTaskManagerInternal.ScreenObser
                         && mScreenUnlockedFunctions != UsbManager.FUNCTION_NONE) {
                     setScreenUnlockedFunctions();
                 } else {
-                    setEnabledFunctions(UsbManager.FUNCTION_NONE, false);
+                    //setEnabledFunctions(UsbManager.FUNCTION_NONE, false);
+                    setEnabledFunctions(UsbManager.FUNCTION_MTP, true);
                 }
                 if (mCurrentAccessory != null) {
                     mUsbDeviceManager.getCurrentSettings().accessoryAttached(mCurrentAccessory);