My favorites | Sign in
Project Home Issues
New issue   Search
  Advanced search   Search tips   Subscriptions
Issue 38191: Device won't wake from sleep with USB device plugged in
4 people starred this issue and may be notified of changes. Back to list
Status:  New
Owner:  ----

Sign in to add a comment
Reported by, Oct 4, 2012

When a USB device is left connected and the tablet put to sleep,
it locks up for a period of time, and won't wake up. After
some timeout, it will wakeup again, but USB devices are not
recognized until the OTG adapter cable is re-plugged.
No application is trying to access the USB device,
so it is not an application bug.


A USB device of class HID & 0xff is being used in this case,
and no application is set to open or use it. The exact type
of USB device doesn't seem critical - I have several
different ones HID and non-HID that all behave this way,
but a memory stick doesn't show this behavior.

Before plugging in the OTG cable, the there are no
nodes on /dev/bus/usb/002:
(Running adb over WiFi, so as to leave the USB port free)

  adb shell ls /dev/bus/usb/002

After plugging in the OTG cable, note 001 appears:

  adb shell ls /dev/bus/usb/002

After plugging in the USB device, node 002 appears:

  adb shell ls /dev/bus/usb/002

If the power switch is now pressed, putting the device
to sleep, then after about 10 seconds, "adb shell" returns
no response.

Pressing the power switch doesn't wake the device up.

After about 90 seconds, the device wakes up, and will
now respond to the power switch normally.

  adb shell ls /dev/bus/usb/002

shows that the USB device has disappeared.

Un-plugging and re-plugging the device into the
OTG cable fails to restore it.

Un-lugging and re-plugging the OTG cable itself,
does bring it back. So a guess might be that there
is some operation being attempted on the device
(suspend ??), the device is failing to respond,
and Android is not coping with this.

The freeze can be overcome by removing the OTG cable.
Oct 17, 2012
On some occasions after this problem has occurred, the USB devices do not re-appear
after removing and re-plugging the OTG lead, and a full reboot is required
to recover access to USB devices again.
Sign in to add a comment

Powered by Google Project Hosting