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Diffstat (limited to 'Documentation/ABI/testing/sysfs-devices-power')
-rw-r--r-- | Documentation/ABI/testing/sysfs-devices-power | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power index 431bfd7e65c..6123c523bfd 100644 --- a/Documentation/ABI/testing/sysfs-devices-power +++ b/Documentation/ABI/testing/sysfs-devices-power | |||
@@ -51,3 +51,29 @@ Description: | |||
51 | drivers. Changing this attribute to "on" prevents the driver | 51 | drivers. Changing this attribute to "on" prevents the driver |
52 | from power managing the device at run time. Doing that while | 52 | from power managing the device at run time. Doing that while |
53 | the device is suspended causes it to be woken up. | 53 | the device is suspended causes it to be woken up. |
54 | |||
55 | What: /sys/devices/.../power/async | ||
56 | Date: January 2009 | ||
57 | Contact: Rafael J. Wysocki <rjw@sisk.pl> | ||
58 | Description: | ||
59 | The /sys/devices/.../async attribute allows the user space to | ||
60 | enable or diasble the device's suspend and resume callbacks to | ||
61 | be executed asynchronously (ie. in separate threads, in parallel | ||
62 | with the main suspend/resume thread) during system-wide power | ||
63 | transitions (eg. suspend to RAM, hibernation). | ||
64 | |||
65 | All devices have one of the following two values for the | ||
66 | power/async file: | ||
67 | |||
68 | + "enabled\n" to permit the asynchronous suspend/resume; | ||
69 | + "disabled\n" to forbid it; | ||
70 | |||
71 | The value of this attribute may be changed by writing either | ||
72 | "enabled", or "disabled" to it. | ||
73 | |||
74 | It generally is unsafe to permit the asynchronous suspend/resume | ||
75 | of a device unless it is certain that all of the PM dependencies | ||
76 | of the device are known to the PM core. However, for some | ||
77 | devices this attribute is set to "enabled" by bus type code or | ||
78 | device drivers and in that cases it should be safe to leave the | ||
79 | default value. | ||