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

Tejun Heo
2011-11-03T14:30:15Z

Hello,

On Thu, Nov 3, 2011 at 7:21 AM, Lin Ming <ming.m.lin@intel.com> 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