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SubjectRe: [linux-usb-devel] USB autosuspend and turning of usb pendrive leds
Alan Stern wrote:
> 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?

Yes, the one that comes and goes as I plug in one of the USB-sticks I ue for
testing.

> 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.
>

I did read them back and it 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.
>

How does this relate to your "It works fine on my systems" remark, do I need to
do anything other the unmounting the paritions to make the device eligible for
autosuspend, like unbind the sd driver or even the usb-storage driver?

If so I must say I find that a little counter intuitive.

Regards,

Hans


p.s.

As always, please keep me CC-ed, not on the list.

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