From: Pavel Machek <pavel@ucw.cz>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Linux PM <linux-pm@osdl.org>
Subject: Re: [RFC][PATCH] swsusp: warn about USB devices in documentation
Date: Mon, 20 Feb 2006 17:43:10 +0100 [thread overview]
Message-ID: <20060220164309.GC19156@elf.ucw.cz> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0602201139480.18560-100000@netrider.rowland.org>
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On Po 20-02-06 11:41:49, Alan Stern wrote:
> On Mon, 20 Feb 2006, Pavel Machek wrote:
>
> > Hi!
> > > > > Can you update the patch to fix this paragraph?
> > > >
> > > > Well, this is talking about suspend-to-disk... That is expected to
> > > > power down machine, without providing USB bus power. If box
> > > > suspends-to-disk and leaves USB up, something is wrong with the
> > > > machine.
> > >
> > > Oh, sorry, I didn't realize that.
> > >
> > > Isn't there an ACPI mode that powers down most things (including RAM) but
> > > is able to respond to wakeup events? I can't remember the mode's name,
> > > except that it's almost certainly "S" followed by some meaningless number
> > > followed by some unhelpful word. :-) Since USB plug/unplug is potentially
> > > a wakeup event, such a mode must provide suspend power to the USB
> > > controller.
> >
> > Maybe S4 does that, but I'm not sure...
> >
> > > Does swsusp still support these not-completely-powered-off modes?
> >
> > Yes. echo platform > /sys/power/disk.
>
> So if you did that, you could suspend-to-disk while leaving USB up, right?
> Without anything being wrong with the machine.
Not sure... never seen such machine. My impression is that USB needs
more power than RAMs in self-refresh mode...
You are right that maybe some machines where USB has power in S4
exist.. I never seen one.
Pavel
--
Web maintainer for suspend.sf.net (www.sf.net/projects/suspend) wanted...
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next prev parent reply other threads:[~2006-02-20 16:43 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-19 22:06 [RFC][PATCH] swsusp: warn about USB devices in documentation Rafael J. Wysocki
2006-02-19 22:13 ` Pavel Machek
2006-02-20 3:50 ` Alan Stern
2006-02-20 10:34 ` Pavel Machek
2006-02-20 13:23 ` Rafael J. Wysocki
2006-02-20 15:34 ` Alan Stern
2006-02-20 16:37 ` Pavel Machek
2006-02-20 16:41 ` Alan Stern
2006-02-20 16:43 ` Pavel Machek [this message]
2006-02-20 18:23 ` Patrick Mochel
2006-02-20 19:45 ` Alan Stern
2006-02-20 20:13 ` Patrick Mochel
2006-02-20 20:30 ` Alan Stern
2006-02-20 20:41 ` Pavel Machek
2006-02-20 10:36 ` Rafael J. Wysocki
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