Merge remote branch 'linus/master' into x86/bootmem

[sfrench/cifs-2.6.git] / Documentation / ABI / testing / sysfs-bus-usb

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index deb6b489e4e5da71d80f367961dc46cfafcd8f08..a07c0f366f91827fa869ec4751d3586280aff2d4 100644 (file)
--- 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>
 Description:
                Each USB device directory will contain a file named
                power/level.  This file holds a power-level setting for
-               the device, one of "on", "auto", or "suspend".
+               the device, either "on" or "auto".
 
                "on" means that the device is not allowed to autosuspend,
                although normal suspends for system sleep will still
                be honored.  "auto" means the device will autosuspend
                and autoresume in the usual manner, according to the
-               capabilities of its driver.  "suspend" means the device
-               is forced into a suspended state and it will not autoresume
-               in response to I/O requests.  However remote-wakeup requests
-               from the device may still be enabled (the remote-wakeup
-               setting is controlled separately by the power/wakeup
-               attribute).
+               capabilities of its driver.
 
                During normal use, devices should be left in the "auto"
-               level.  The other levels are meant for administrative uses.
+               level.  The "on" level is meant for administrative uses.
                If you want to suspend a device immediately but leave it
                free to wake up in response to I/O requests, you should
                write "0" to power/autosuspend.
 
+               Device not capable of proper suspend and resume should be
+               left in the "on" level.  Although the USB spec requires
+               devices to support suspend/resume, many of them do not.
+               In fact so many don't that by default, the USB core
+               initializes all non-hub devices in the "on" level.  Some
+               drivers may change this setting when they are bound.
+
 What:          /sys/bus/usb/devices/.../power/persist
 Date:          May 2007
 KernelVersion: 2.6.23