USB: Allow autosuspend delay to equal 0

This patch (as867) adds an entry for the new power/autosuspend
attribute in Documentation/ABI/testing, and it changes the behavior of
the delay value.  Now a delay of 0 means to autosuspend as soon as
possible, and negative values will prevent autosuspend.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 16 insertions, 1 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
new file mode 100644
index 000000000000..00a84326325f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -0,0 +1,15 @@
+What:           /sys/bus/usb/devices/.../power/autosuspend
+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/autosuspend.  This file holds the time (in seconds)
+                the device must be idle before it will be autosuspended.
+                0 means the device will be autosuspended as soon as
+                possible.  Negative values will prevent the device from
+                being autosuspended at all, and writing a negative value
+                will resume the device if it is already suspended.
+
+                The autosuspend delay for newly-created devices is set to
+                the value of the usbcore.autosuspend module parameter.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 12533a958c51..2017942e0966 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1792,7 +1792,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         for newly-detected USB devices (default 2).  This
                         is the time required before an idle device will be
                         autosuspended.  Devices for which the delay is set
-                        to 0 won't be autosuspended at all.
+                        to a negative value won't be autosuspended at all.
 
         usbhid.mousepoll=
                         [USBHID] The interval which mice are to be polled at.