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

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Message-ID: <Pine.LNX.4.44L0.0709221610170.31951-100000@netrider.rowland.org>
Date:	Sat, 22 Sep 2007 16:12:16 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Hans de Goede <j.w.r.degoede@....nl>
cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	USB development list <linux-usb-devel@...ts.sourceforge.net>
Subject: Re: [linux-usb-devel] USB autosuspend and turning of usb pendrive
 leds

On Sat, 22 Sep 2007, Hans de Goede wrote:

> >> 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?

You shouldn't have to do anything.  Mounted or unmounted, bound to sd
or not bound, it shouldn't matter.  Provided the device isn't being
used, it ought to autosuspend.

I repeat: To find out what is really happening, you should use usbmon.

Alan Stern

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