From: Oliver Neukum <oliver@neukum.org>
To: Pavel Machek <pavel@ucw.cz>, linux-kernel@vger.kernel.org,
       linux-usb-devel@lists.sourceforge.net
Subject: Re: error to be returned while suspended
Date: Thu, 5 Oct 2006 09:07:26 +0200
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Am Donnerstag, 5. Oktober 2006 00:44 schrieben Sie:
> Hi!
> 
> > > > which error should a character device return if a read/write cannot be
> > > > serviced because the device is suspended? Shouldn't there be an error
> > > > code specific to that?
> > > 
> > > If you are talking system suspend, then userspace should not run while
> > > devices are suspended.
> > > 
> > > If you are talking runtime suspend, you should probably just wake the
> > > device up on first access.
> > 
> > Do you really think a device driver should override an explicitely
> > selected power state?
> 
> (So we are talking runtime suspend?)

Yes. Otherwise the patch would have been ready two days ago.
But if I am implenting this, I'll do a full implementation.

> No, I do not know what the right interface is. I started to suspect
> that drivers should suspend/resume devices automatically, without
> userland help. Maybe having autosuspend_timeout in sysfs is enough.

If you do this at kernel level, you'll screw up any demon implementing
a power policy to stay within the budget.

	Regards
		Oliver
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