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    SubjectRe: [linux-usb-devel] USB autosuspend and turning of usb pendrive leds
    On Sat, 22 Sep 2007, Hans de Goede wrote:

    > I'm afraid that that doesn't work for usb mass-storage devices.
    > Here is what I did:
    > 1) kill hal
    > 2) insert usb stick -> led lights
    > 3):
    > echo -n 1 > /sys/bus/usb/devices/.../power/autosuspend
    > echo -n auto > /sys/bus/usb/devices/.../power/level
    > 4) wait
    > Nothing happens, where as sending "suspend" to power/level does turn the led
    > off.

    I don't know what went wrong. It works fine on my systems. You did
    fill in the correct device path for the "...", right? And you don't
    need the "-n" -- adding it shouldn't matter, but you should try reading
    back the contents of those files to make sure the values did get
    written correctly.

    > Now call me naive, but I would expect a mass-storage devices with no
    > partitions mounted to autosuspend when autosuspend is enabled for that device.

    Yes, that is naive. The driver has no way to tell whether or not any
    partitions are mounted. Furthermore, you might very well want to
    access the raw device without mounting any partitions (database
    managers frequently do such things to reduce I/O overhead), in which
    case you certainly would not the device to be autosuspended.

    > And yes I'm pretty sure nothing else is talking to the device.

    You can be absolutely certain by using usbmon (see
    Documentation/usb/usbmon.txt). It will also show whether any suspends
    or resumes are actually being sent.

    Alan Stern

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      Last update: 2007-09-22 16:33    [W:0.021 / U:45.616 seconds]
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