linux-kernel - Re: [PATCH 0/3] ata port runtime power management support

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Date:	Thu, 03 Nov 2011 22:21:47 +0800
From:	Lin Ming <ming.m.lin@...el.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Jeff Garzik <jgarzik@...ox.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	James Bottomley <JBottomley@...allels.com>,
	"Huang, Ying" <ying.huang@...el.com>,
	"Zhang, Rui" <rui.zhang@...el.com>
Subject: Re: [PATCH 0/3] ata port runtime power management support

On Wed, 2011-11-02 at 23:17 +0800, Tejun Heo wrote:
> Hello,
> 
> On Wed, Nov 02, 2011 at 02:21:37PM +0800, Lin Ming wrote:
> > These 3 patches add ata port runtime pm support, which is done through scsi layer.
> > scsi host runtime pm mechanism is already there(scsi_pm.c).
> > These patches add hooks for ata port.
> > 
> > Lin Ming (3):
> >       scsi: fix potential dead lock for host runtime pm
> >       scsi: add hooks for host runtime power management
> >       ata: implement ata port runtime pm hooks
> 
> Hmmm.... Some questions.
> 
> * How much does this add on top of hardware timed auto spindown and
>   dynamic link power management?

Sorry, I don't understand this question.
What do you mean?

> 
> * Do the added benefits justify yet another runtime powersaving
>   mechanism?

There will be ACPI firmware which supports ata port runtime D3Cold.
To enable ata port runtime PM is the first step.

> 
> * Any way we can tie the other stuff with overall runtime PM?

What's the other stuff?
Do you mean tie disk/link/port/controller stuff with overall runtime PM?

I'm not sure for now. Need to think about it more.



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