[Differential] [Accepted] D2018: Introduce Annapurna Labs AHCI support

[Jia-Shiun Li]

On Sat, Mar 14, 2015 at 9:29 AM, imp (Warner Losh) <
phabric-noreply at freebsd.org> wrote:

> imp accepted this revision.
> imp added a comment.
> This revision is now accepted and ready to land.
>
> Thanks for the comments. Still not sure what an Annapurna is....
>
> REVISION DETAIL
>   https://reviews.freebsd.org/D2018
>
> To: zbb, mav, smh, imp
> Cc: freebsd-arm
>

Probably SoC from Annapurna Labs.
https://gigaom.com/2015/01/22/confirmed-amazon-is-buying-annapurna-labs/

The init part probably should have been done in boot loader when initing
hardware.
The AHCI standard was designed in the way that system designers have room
to adjust.
E.g. use PI to indicate only two ports were connected on a notebook when
silicon supports 6, so a generic driver can detect it and not to assume it
can use all 6 ports.

Not sure about Annapurna's implementation.
Intel's ICH/PCH implement these read-only registers as write once registers
after powered on, so BIOS will always be the only one modifying,
and drivers see them as read-only.
It is also possible that implementations choose to init by values in
external
ROM/flash, internal fuse, or strapping pins.

It will need docs from Annapurna, spec or errata, to see if it disagree
with AHCI
in any ways, and if there is better alternative to quirks.



-Jia-Shiun.