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>
diff --git a/Documentation/ABI/obsolete/sysfs-bus-usb b/Documentation/ABI/obsolete/sysfs-bus-usb
new file mode 100644
index 0000000..bd096d3
--- /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.