Re: [PATCH RFC] ahci: implement handoff quirk

[Jeff Garzik <jeff@garzik.org>]

Tejun Heo wrote:
> ahci 1.2 has an exciting! new feature called BIOS/OS handoff which
> basically is there to allow BIOS to keep tinkering with the controller
> even after OS starts executing.  I have no idea what this is useful
> for but it's there and we need to do it.
> 
> This patch implements the handoff as FIXUP_HEADER as the controller
> needs to be claimed before the OS changes any configuration including
> IRQ routing.
> 
> I'm yet to see any controller which actually requires this, so it's
> not for inclusion yet.  Maybe keep this in a separate branch?
> 
> RFC, DON'T COMMIT

We probably need to do this...

it's not a controller requirement but a BIOS one, so in theory even an 
existing, deployed AHCI 1.2 platform could suddenly require BIOS/OS 
handoff, if a BIOS update suddenly starts doing new and weird stuff in SMI.

Note that we need to do BIOS/OS handoff upon resume as well as at boot time.

	Jeff