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-rw-r--r--Documentation/ABI/testing/sysfs-bus-usb39
1 files changed, 11 insertions, 28 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index a07c0f366f91..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
@@ -159,3 +131,14 @@ Description:
159 device. This is useful to ensure auto probing won't 131 device. This is useful to ensure auto probing won't
160 match the driver to the device. For example: 132 match the driver to the device. For example:
161 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id 133 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
134
135What: /sys/bus/usb/device/.../avoid_reset_quirk
136Date: December 2009
137Contact: Oliver Neukum <oliver@neukum.org>
138Description:
139 Writing 1 to this file tells the kernel that this
140 device will morph into another mode when it is reset.
141 Drivers will not use reset for error handling for
142 such devices.
143Users:
144 usb_modeswitch