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Message-ID: <Pine.LNX.4.44L0.0808221810060.9561-100000@netrider.rowland.org>
Date: Fri, 22 Aug 2008 18:14:51 -0400 (EDT)
From: Alan Stern <stern@...land.harvard.edu>
To: Pavel Machek <pavel@...e.cz>
cc: Oliver Neukum <oneukum@...e.de>,
<linux-pm@...ts.linux-foundation.org>,
<James.Bottomley@...senpartnership.com>,
Linux-pm mailing list <linux-pm@...ts.osdl.org>,
kernel list <linux-kernel@...r.kernel.org>, <teheo@...ell.com>
Subject: Re: [linux-pm] Power management for SCSI
On Fri, 22 Aug 2008, Pavel Machek wrote:
> Hi!
>
> > > - suspending has side effects
> >
> > I'm not sure what you mean by that. Suspension always has side effects
> > of one kind or another.
> >
> > > Suspension in USB has always side effects. That's not true for other
> > > subsystems.
> >
> > Name one. At the very least, suspending a device means you can't use
> > it again without first calling the driver's resume method. That's a
> > side effect.
>
> IDE, actually. I don't think it is relevant, but you can do hdparm -y,
> and it will automatically spin up when you try to talk to it next
> time.
It's a matter of definitions... "hdparm -y" doesn't call the driver's
suspend method, so in some sense it isn't truly a suspend.
But it's true that some systems can power down more or less
transparently (with restart latency as the only visible side effect).
Alan Stern
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