Re: [linux-usb-devel] USB autosuspend and turning of usb pendrive leds

[Hans de Goede <j.w.r.degoede@hhs.nl>]

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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