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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2010-01-22 02:55:25 -0500
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2010-01-22 02:55:25 -0500
commit7755726fe90a8b253659756e6de68c1a55aa427f (patch)
treea3523fa77e07854db3b8089e3066a55ea997060c /Documentation/ABI/testing/sysfs-bus-usb
parent3bf127637e22ddf95e67e10a23c339cee3d52429 (diff)
parent92dcffb916d309aa01778bf8963a6932e4014d07 (diff)
Merge commit 'v2.6.33-rc5' into next
Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-usb')
-rw-r--r--Documentation/ABI/testing/sysfs-bus-usb18
1 files changed, 10 insertions, 8 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index deb6b489e4e5..a07c0f366f91 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -21,25 +21,27 @@ Contact: Alan Stern <stern@rowland.harvard.edu>
21Description: 21Description:
22 Each USB device directory will contain a file named 22 Each USB device directory will contain a file named
23 power/level. This file holds a power-level setting for 23 power/level. This file holds a power-level setting for
24 the device, one of "on", "auto", or "suspend". 24 the device, either "on" or "auto".
25 25
26 "on" means that the device is not allowed to autosuspend, 26 "on" means that the device is not allowed to autosuspend,
27 although normal suspends for system sleep will still 27 although normal suspends for system sleep will still
28 be honored. "auto" means the device will autosuspend 28 be honored. "auto" means the device will autosuspend
29 and autoresume in the usual manner, according to the 29 and autoresume in the usual manner, according to the
30 capabilities of its driver. "suspend" means the device 30 capabilities of its driver.
31 is forced into a suspended state and it will not autoresume
32 in response to I/O requests. However remote-wakeup requests
33 from the device may still be enabled (the remote-wakeup
34 setting is controlled separately by the power/wakeup
35 attribute).
36 31
37 During normal use, devices should be left in the "auto" 32 During normal use, devices should be left in the "auto"
38 level. The other levels are meant for administrative uses. 33 level. The "on" level is meant for administrative uses.
39 If you want to suspend a device immediately but leave it 34 If you want to suspend a device immediately but leave it
40 free to wake up in response to I/O requests, you should 35 free to wake up in response to I/O requests, you should
41 write "0" to power/autosuspend. 36 write "0" to power/autosuspend.
42 37
38 Device not capable of proper suspend and resume should be
39 left in the "on" level. Although the USB spec requires
40 devices to support suspend/resume, many of them do not.
41 In fact so many don't that by default, the USB core
42 initializes all non-hub devices in the "on" level. Some
43 drivers may change this setting when they are bound.
44
43What: /sys/bus/usb/devices/.../power/persist 45What: /sys/bus/usb/devices/.../power/persist
44Date: May 2007 46Date: May 2007
45KernelVersion: 2.6.23 47KernelVersion: 2.6.23