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130 files changed, 15264 insertions, 1950 deletions
diff --git a/Documentation/usb/power-management.txt b/Documentation/usb/power-management.txt index b29d8e56cf2..c9ffa9ced7e 100644 --- a/Documentation/usb/power-management.txt +++ b/Documentation/usb/power-management.txt @@ -2,7 +2,7 @@ Alan Stern <stern@rowland.harvard.edu> - December 11, 2009 + October 28, 2010 @@ -107,9 +107,14 @@ allowed to issue dynamic suspends. The user interface for controlling dynamic PM is located in the power/ subdirectory of each USB device's sysfs directory, that is, in /sys/bus/usb/devices/.../power/ where "..." is the device's ID. The -relevant attribute files are: wakeup, control, and autosuspend. -(There may also be a file named "level"; this file was deprecated -as of the 2.6.35 kernel and replaced by the "control" file.) +relevant attribute files are: wakeup, control, and +autosuspend_delay_ms. (There may also be a file named "level"; this +file was deprecated as of the 2.6.35 kernel and replaced by the +"control" file. In 2.6.38 the "autosuspend" file will be deprecated +and replaced by the "autosuspend_delay_ms" file. The only difference +is that the newer file expresses the delay in milliseconds whereas the +older file uses seconds. Confusingly, both files are present in 2.6.37 +but only "autosuspend" works.) power/wakeup @@ -140,33 +145,36 @@ as of the 2.6.35 kernel and replaced by the "control" file.) suspended and autoresume was not allowed. This setting is no longer supported.) - power/autosuspend + power/autosuspend_delay_ms This file contains an integer value, which is the - number of seconds the device should remain idle before - the kernel will autosuspend it (the idle-delay time). - The default is 2. 0 means to autosuspend as soon as - the device becomes idle, and negative values mean - never to autosuspend. You can write a number to the - file to change the autosuspend idle-delay time. - -Writing "-1" to power/autosuspend and writing "on" to power/control do -essentially the same thing -- they both prevent the device from being -autosuspended. Yes, this is a redundancy in the API. + number of milliseconds the device should remain idle + before the kernel will autosuspend it (the idle-delay + time). The default is 2000. 0 means to autosuspend + as soon as the device becomes idle, and negative + values mean never to autosuspend. You can write a + number to the file to change the autosuspend + idle-delay time. + +Writing "-1" to power/autosuspend_delay_ms and writing "on" to +power/control do essentially the same thing -- they both prevent the +device from being autosuspended. Yes, this is a redundancy in the +API. (In 2.6.21 writing "0" to power/autosuspend would prevent the device from being autosuspended; the behavior was changed in 2.6.22. The power/autosuspend attribute did not exist prior to 2.6.21, and the power/level attribute did not exist prior to 2.6.22. power/control -was added in 2.6.34.) +was added in 2.6.34, and power/autosuspend_delay_ms was added in +2.6.37 but did not become functional until 2.6.38.) Changing the default idle-delay time ------------------------------------ -The default autosuspend idle-delay time is controlled by a module -parameter in usbcore. You can specify the value when usbcore is -loaded. For example, to set it to 5 seconds instead of 2 you would +The default autosuspend idle-delay time (in seconds) is controlled by +a module parameter in usbcore. You c |