Re: [PATCH] libata: Add ALPM power state accounting to the AHCI driver

[Jeff Garzik <jgarzik@pobox.com>]

On 11/16/2009 10:21 AM, Arjan van de Ven wrote:
> On Mon, 16 Nov 2009 23:59:39 +0900
> Tejun Heo<tj@kernel.org>  wrote:
>
>> Arjan van de Ven wrote:
>>> is there a hardware way to ask for the link status via a link level
>>> thing? I thought the sata_scr_read() was by definition a host thing
>>
>> sata_scr_read() will do the right thing given the link parameter
>> although it needs to be called from EH context for PMP links.  For
>> now, just making the functions take @link param and passing it around
>> should do.
>>
>
> I'm sorry it just does not make sense to me anymore.
> if this moves to be a link level thing, then the statistics also need
> to be kept link level, and thus exported link level, and I don't think
> that exists.

It is already link-level in hardware (ie. in reality), in the sata_scr_* 
interface, and in the accounting stats you [quite correctly] added to 
struct ata_link in your patch.

The only thing -not- at link level is the userland interface, which 
instead uses host-level granularity.

	Jeff