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authorJens Axboe <jens.axboe@oracle.com>2010-05-21 21:27:26 +0200
committerJens Axboe <jens.axboe@oracle.com>2010-05-21 21:27:26 +0200
commitee9a3607fb03e804ddf624544105f4e34260c380 (patch)
treece41b6e0fa10982a306f6c142a92dbf3c9961284 /Documentation/ABI/obsolete/sysfs-bus-usb
parentpipe: set lower and upper limit on max pages in the pipe page array (diff)
parentMerge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jac... (diff)
downloadlinux-ee9a3607fb03e804ddf624544105f4e34260c380.tar.xz
linux-ee9a3607fb03e804ddf624544105f4e34260c380.zip
Merge branch 'master' into for-2.6.35
Conflicts: fs/ext3/fsync.c Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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+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.