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

[Jeff Garzik]

Kristen Carlson Accardi wrote:
> On Mon, 02 Jun 2008 09:03:04 -0400
> Mark Lord <liml@xxxxxx> wrote:
>
> > Jeff Garzik wrote:
> > > Alan Cox wrote:
> > > > > If you are talking about SATA -- incorrect.
> > > > >
> > > > > The patch deals with policy, and the user MUST have the ability to 
> > > > > control this stuff.  Otherwise you create a situation where the user 
> > > > > might be denied hotplug use in valid cases, or similar negative 
> > > > > situations.
> > > > The policy isn't however complicated. Tejun added the stuff for forcing
> > > > cable type and mode on setup and has therefore written all the per device
> > > > setup code we might need. Alternatively a single
> > > >
> > > >     foo=1/0
> > > >
> > > > option has been fine for acpi and will do fine for this. Total additional
> > > > cost - 1 line.
> > > The key requirement is per-port control.  Ideally via hdparm or another 
> > > userspace tool, but kernel command line (module options) or sysfs would 
> > > be just fine too.  And agreed, the minimal you need is simply 1/0 for 
> > > the port's policy.
> > ..
> >
> > Btw.. hdparm-8.7 (unreleased) can grok /sys now, so that interface is
> > as good as any from a userspace viewpoint now.
> >
> > For the power-off of unused ports, the current patch still sounds
> > extremely vendor-specific (Intel).
>
> Wrong - this patch is implemented according to the AHCI spec and
> has absolutely nothing vendor specific in it.

ITHM AHCI-specific, and not usable by non-AHCI SATA controllers -- which 
we would want in any solution.

	Jeff




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