linux-kernel - Re: [PATCH] ata: ahci: power off unused ports

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Message-ID: <20080602111644.54738d57@appleyard>
Date:	Mon, 2 Jun 2008 11:16:44 -0700
From:	Kristen Carlson Accardi <kristen.c.accardi@...el.com>
To:	Jeff Garzik <jeff@...zik.org>
Cc:	Mark Lord <liml@....ca>, Alan Cox <alan@...rguk.ukuu.org.uk>,
	Pavel Machek <pavel@....cz>, Theodore Tso <tytso@....edu>,
	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ata: ahci: power off unused ports

On Mon, 02 Jun 2008 14:15:27 -0400
Jeff Garzik <jeff@...zik.org> wrote:

> Kristen Carlson Accardi wrote:
> > Here you can see that it would be very easy for another driver
> > to just add code to set the NO_HOTPLUG flag and then this code
> > will work for them as well, since we power off the phy using
> > DET which is specified by SATA.
> 
> > here's that code:
> 
> Agreed.  The main discussion in this sub-thread is more about user 
> interface.  The user interface in this case, a module option, is 
> specific to AHCI.
> 
> Surely you can see how it is a bit silly to force each driver writer to 
> create the same user interface in each driver, to support a generic concept.
> 
> 	Jeff
> 
> 
Not all drivers will need a user interface to turn off hotplug
I would think.  At any rate - I would think it'd be better to let
driver writers decide how they want their drivers to behave wrt
hotplug and power instead of forcing a generic policy on everyone.

This patch would provide users of AHCI controllers a way to save
power now, while you work on the grand scheme for polling/turning on off
hotplug via sysfs.  It's an interim solution that impacts nobody but
ahci users and is can be easily integrated into whatever solution you
eventually work out.


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