diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2010-04-02 13:22:16 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-05-20 13:21:37 -0700 |
| commit | a90309860b0935805d49e75499fb8dc59fea8e94 (patch) | |
| tree | 2d5ed0376a0f0ead945afdaa11be00a48bc0af6c /Documentation/ABI/obsolete/sysfs-bus-usb | |
| parent | 9e18c821659d836bd63f88df3c19729327728496 (diff) | |
USB: deprecate the power/level sysfs attribute
This patch (as1367) deprecates USB's power/level sysfs attribute in
favor of the power/control attribute provided by the runtime PM core.
The two attributes do the same thing.
It would be nice to replace power/level with a symlink to
power/control, but at the moment sysfs doesn't offer any way to do so.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation/ABI/obsolete/sysfs-bus-usb')
| -rw-r--r-- | Documentation/ABI/obsolete/sysfs-bus-usb | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/ABI/obsolete/sysfs-bus-usb b/Documentation/ABI/obsolete/sysfs-bus-usb new file mode 100644 index 00000000000..bd096d33fbc --- /dev/null +++ b/Documentation/ABI/obsolete/sysfs-bus-usb @@ -0,0 +1,31 @@ +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, 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. + + During normal use, devices should be left in the "auto" + 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. + + This file is deprecated and will be removed after 2010. + Use the power/control file instead; it does exactly the + same thing. |