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UsbDeviceManager: Don't unnecessarily touch properties

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Before setting the properties persist.sys.usb.config or sys.usb.config,
check the existing values. If the values are the same as what we'd set it
to, don't perform the set.

Any USB property set, even if setting the property to the value it already
has, triggers one of the "on property" triggers in system/core/rootdir/init.usb.rc .
The script then reconfigures the driver unnecessarily, which causes instability
and dropped connections when trying to use ADB.

Avoid this instability by not performing property sets which would have
no effect.

Bug: 21404762
Bug: 18905620
Change-Id: Id3c2543308df994a0114a0661e20ca799c2dc0e8
This commit is contained in:
Nick Kralevich
2015-06-02 16:56:06 -07:00
parent 233241f13d
commit 2f7fa3ed77
1 changed files with 16 additions and 3 deletions
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19
services/usb/java/com/android/server/usb/UsbDeviceManager.java
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@@ -411,6 +411,16 @@ public class UsbDeviceManager {
sendMessageDelayed(msg, (connected == 0) ? UPDATE_DELAY : 0);
}
private void updatePersistentProperty() {
String newValue = mAdbEnabled ? "adb" : "none";
String value = SystemProperties.get(UsbManager.ADB_PERSISTENT_PROPERTY);
if (DEBUG) { Slog.d(TAG, "updatePersistentProperty newValue=" + newValue + " value=" + value); }
if (!newValue.equals(value)) {
SystemProperties.set(UsbManager.ADB_PERSISTENT_PROPERTY, mAdbEnabled ? "adb" : "none");
}
waitForState(newValue);
}
private boolean waitForState(String state) {
// wait for the transition to complete.
// give up after 1 second.
@@ -426,7 +436,10 @@ public class UsbDeviceManager {
private boolean setUsbConfig(String config) {
if (DEBUG) Slog.d(TAG, "setUsbConfig(" + config + ")");
// set the new configuration
SystemProperties.set(UsbManager.USB_SETTINGS_PROPERTY, config);
String oldConfig = SystemProperties.get(UsbManager.USB_SETTINGS_PROPERTY);
if (!config.equals(oldConfig)) {
SystemProperties.set(UsbManager.USB_SETTINGS_PROPERTY, config);
}
return waitForState(config);
}
@@ -436,7 +449,7 @@ public class UsbDeviceManager {
mAdbEnabled = enable;
// Due to the persist.sys.usb.config property trigger, changing adb state requires
// persisting default function
SystemProperties.set(UsbManager.ADB_PERSISTENT_PROPERTY, mAdbEnabled ? "adb" : "none");
updatePersistentProperty();
// After persisting them use the lock-down aware function set
setEnabledFunctions(getDefaultFunctions());
updateAdbNotification();
@@ -610,7 +623,7 @@ public class UsbDeviceManager {
break;
case MSG_SYSTEM_READY:
setUsbConfig(mCurrentFunctions);
SystemProperties.set(UsbManager.ADB_PERSISTENT_PROPERTY, mAdbEnabled ? "adb" : "none");
updatePersistentProperty();
updateUsbNotification();
updateAdbNotification();
updateUsbState();