Re: [PATCH 0/3] ata port runtime power management support
From: Tejun Heo
Date: Thu Nov 03 2011 - 10:30:22 EST
Hello,
On Thu, Nov 3, 2011 at 7:21 AM, Lin Ming <ming.m.lin@xxxxxxxxx> wrote:
>> * 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?
I was curious about the amount of additional power saving on top of
the existing PM features.
>> * 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.
libata can already turn off unused ports although it wouldn't go as
far as putting the whole controller into D3.
>> * 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?
Hardware initiated spin-down (hdparm -S) and link power saving (look
for ata_lpm_*). It would be great if there's an overall design how
they interact before adding yet another PM vector.
Thanks.
--
tejun
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