Message-ID: <48443C3C.3010401@redhat.com>
Date: Mon, 02 Jun 2008 14:30:20 -0400
From: Ric Wheeler <rwheeler@redhat.com>
Reply-To: rwheeler@redhat.com
Organization: Red Hat
User-Agent: Thunderbird 2.0.0.14 (X11/20080501)
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To: kristen.c.accardi@intel.com
CC: Jeff Garzik <jeff@garzik.org>, Mark Lord <liml@rtr.ca>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>, Pavel Machek <pavel@ucw.cz>,
       Theodore Tso <tytso@mit.edu>, linux-ide@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ata: ahci: power off unused ports
References: <20080508161008.59361de5@appleyard>	<20080527030854.GC7515@mit.edu>	<20080527143202.4bab5bf0@appleyard>	<20080527225926.GE6843@mit.edu>	<20080527163251.04054a74@appleyard>	<20080531080015.GG5405@ucw.cz>	<4842F5A8.9020708@garzik.org>	<20080602080440.25fc663c@core>	<4843A4A7.3020809@garzik.org>	<4843EF88.2040606@rtr.ca>	<48441AA6.8080704@garzik.org>	<20080602100019.3d2d2522@appleyard>	<484431AB.7010005@garzik.org>	<20080602104753.3f24087d@appleyard>	<484438BF.7070303@garzik.org> <20080602111644.54738d57@appleyard>
In-Reply-To: <20080602111644.54738d57@appleyard>
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Kristen Carlson Accardi wrote:
> On Mon, 02 Jun 2008 14:15:27 -0400
> Jeff Garzik <jeff@garzik.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.
>   
I like the patch -  it seems that it will help a lot of users out near 
term in a very positive way while we iterate on the broader solution,

ric


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