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Date: Mon, 13 Nov 2006 16:11:30 +0000
From: Alan <alan@lxorguk.ukuu.org.uk>
To: Jeff Garzik <jeff@garzik.org>
Cc: Pavel Machek <pavel@ucw.cz>, John Fremlin <not@just.any.name>,
       kernel list <linux-kernel@vger.kernel.org>, htejun@gmail.com,
       jim.kardach@intel.com, ak@suse.de
Subject: Re: AHCI power saving (was Re: Ten hours on X60s)
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On Mon, 13 Nov 2006 10:32:24 -0500
Jeff Garzik <jeff@garzik.org> wrote:

> Therein lies a key problem.  Turning on all of AHCI's aggressive power 
> management features DOES save a lot of power.  But at the same time, it 
> shortens the life of your hard drive, particularly hard drives that are 
> really PATA, but have a PATA<->SATA bridge glued on the drive to enable 
> connection to SATA controllers.

We already detect PATA over SATA so we can trivially address that (the
knobble check). Similarly we can turn ALPME on using a timer so it kicks
in after long idle periods only, or tie it to laptop mode.

For a laptop type environment with SATA not bridged PATA turning it on is
clearly the right thing to do.

Alan