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authorAlan Stern <stern@rowland.harvard.edu>2010-04-02 13:22:16 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2010-05-20 16:21:37 -0400
commita90309860b0935805d49e75499fb8dc59fea8e94 (patch)
tree2d5ed0376a0f0ead945afdaa11be00a48bc0af6c /Documentation/ABI/testing/sysfs-bus-usb
parent9e18c821659d836bd63f88df3c19729327728496 (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/testing/sysfs-bus-usb')
-rw-r--r--Documentation/ABI/testing/sysfs-bus-usb28
1 files changed, 0 insertions, 28 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index bcebb9eaedce..294aa864a60a 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -14,34 +14,6 @@ Description:
14 The autosuspend delay for newly-created devices is set to 14 The autosuspend delay for newly-created devices is set to
15 the value of the usbcore.autosuspend module parameter. 15 the value of the usbcore.autosuspend module parameter.
16 16
17What: /sys/bus/usb/devices/.../power/level
18Date: March 2007
19KernelVersion: 2.6.21
20Contact: Alan Stern <stern@rowland.harvard.edu>
21Description:
22 Each USB device directory will contain a file named
23 power/level. This file holds a power-level setting for
24 the device, either "on" or "auto".
25
26 "on" means that the device is not allowed to autosuspend,
27 although normal suspends for system sleep will still
28 be honored. "auto" means the device will autosuspend
29 and autoresume in the usual manner, according to the
30 capabilities of its driver.
31
32 During normal use, devices should be left in the "auto"
33 level. The "on" level is meant for administrative uses.
34 If you want to suspend a device immediately but leave it
35 free to wake up in response to I/O requests, you should
36 write "0" to power/autosuspend.
37
38 Device not capable of proper suspend and resume should be
39 left in the "on" level. Although the USB spec requires
40 devices to support suspend/resume, many of them do not.
41 In fact so many don't that by default, the USB core
42 initializes all non-hub devices in the "on" level. Some
43 drivers may change this setting when they are bound.
44
45What: /sys/bus/usb/devices/.../power/persist 17What: /sys/bus/usb/devices/.../power/persist
46Date: May 2007 18Date: May 2007
47KernelVersion: 2.6.23 19KernelVersion: 2.6.23