Re: [PATCH] ata: ahci: power off unused ports

[Kristen Carlson Accardi <kristen.c.accardi@intel.com>]

On Tue, 27 May 2008 18:59:26 -0400
Theodore Tso <tytso@mit.edu> wrote:

> On Tue, May 27, 2008 at 02:32:02PM -0700, Kristen Carlson Accardi wrote:
> > 
> > As far as I know the patch has gone nowhere.  I believe that 
> > Jeff wanted something more flexible than the module parameter that
> > I provided to override the BIOS options.  I am not working on this,
> > I figured he had a pretty firm idea what he wanted so he was better
> > equipped to write the patch.
> 
> Thanks Kristen,
> 
> Can you say which laptops you had tested this on where it saved power?
> (Did you test any Thinkpads, in particular?)  I'm wondering if it's
> worth trying to forward port your patch as a private mod to my kernel;
> 30 to 40 minutes of extra battery life is nothing to sneeze at!
> 
> 						- Ted
> 

I tested this on an Intel mobile software development platform 
with a newer mobile ICH - the power savings were measured at the actual 
component (via probes on the ICH), so I did not measure the power 
savings at the wall socket, although I would expect the power savings
to be even greater on the other side of the power supply.  So in short,
yes, I think it's worth it to give it a try - the patch is pretty
unintrusive, so it should be that difficult a port to do.