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| author | Alan Stern <stern@rowland.harvard.edu> | 2007-03-20 14:59:39 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-04-27 13:28:37 -0700 |
| commit | 2add5229d77a3de08015feef437653e02372162f (patch) | |
| tree | 436109572453656747d6e5b3aec14939b1202ec3 /Documentation | |
| parent | 13f6be01db9ada144f28241f939f4f3f8ec8e40b (diff) | |
| download | linux-2add5229d77a3de08015feef437653e02372162f.tar.bz2 | |
USB: add power/level sysfs attribute
This patch (as874) adds another piece to the user-visible part of the
USB autosuspend interface. The new power/level sysfs attribute allows
users to force the device on (with autosuspend off), force the device
to sleep (with autoresume off), or return to normal automatic operation.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 00a84326325f..f9937add033d 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -13,3 +13,29 @@ Description: The autosuspend delay for newly-created devices is set to the value of the usbcore.autosuspend module parameter. + +What: /sys/bus/usb/devices/.../power/level +Date: March 2007 +KernelVersion: 2.6.21 +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". + + "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). + + During normal use, devices should be left in the "auto" + level. The other levels are 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. |