mirror of
https://github.com/brain-hackers/linux-brain.git
synced 2024-06-09 23:36:23 +09:00
a90309860b
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>
32 lines
1.3 KiB
Plaintext
32 lines
1.3 KiB
Plaintext
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.
|