Re: [RFC][PATCH] ahci: Add support for Promise PDC42819

["Mark Nelson" <mdnelson8@gmail.com>]

On Thu, Sep 4, 2008 at 8:37 PM, Jeff Garzik <jeff@garzik.org> wrote:
> Mark Nelson wrote:
>>
>> On Tue, Sep 2, 2008 at 10:08 PM, Mikael Pettersson <mikpe@it.uu.se> wrote:
>>>
>>> Mark Nelson writes:
>>>  > On Tue, Sep 2, 2008 at 9:19 PM, Jeff Garzik <jeff@garzik.org> wrote:
>>>  > > Mark Nelson wrote:
>>>  > >>
>>>  > >> Add an appropriate entry for the Promise PDC42819 controller. It
>>> has an
>>>  > >> AHCI mode and seems to work correctly with board_ahci.
>>>  > >>
>>>  > >> This chip is found on Promise's FastTrak TX2650 (2 port) and TX4650
>>> (4
>>>  > >> port)
>>>  > >> software-based RAID cards (for which there is a binary driver,
>>> t3sas) and
>>>  > >> can be found on some motherboards, for example the MSI K9A2
>>> Platinum,
>>>  > >> which calls the chip a Promise T3 controller.
>>>  > >>
>>>  > >> Signed-off-by: Mark Nelson <mdnelson8@gmail.com>
>>>  > >> ---
>>>  > >> Apparently this chip also supports SAS disks, will these work with
>>> the
>>>  > >> ahci driver (I've only tested with normal desktop SATA disks)?
>>>  > >
>>>  > > ahci is definitely SATA-only, so I wonder how they modified AHCI to
>>> support
>>>  > > SAS transport...
>>>  >
>>>  > That is a good question. From my understanding the controller is a SAS
>>>  > controller that can drive SATA disks (as I guess all SAS controllers
>>> can
>>>  > do...). Could it be that the controller can be setup to act as an AHCI
>>>  > SATA controller or if the right registers are poked a SAS controller?
>>>
>>> Based on how the sata_promise-supported chips work I'd guess that they
>>> have dual programming interfaces with AHCI for JBOD SATA and a native
>>> one (perhaps just additional control registers) for SAS and raid.
>>>
>>
>> That's interesting; and makes sense. I'm guessing that we won't end up
>> with an open source driver that can do SAS on these chips then... But
>> for now at least we can use them as SATA controllers and if Promise
>> wants to come to the table with specs or datasheets they can in the
>> future. I'm just happy to be able to use my eSATA ports (and perhaps
>> the possibility of getting my hard disk off the SB600, although I should
>> benchmark both controllers before jumping to any conclusions).
>
> FWIW, I'll poke my Promise contacts, but they have gone mostly silent in the
> past year, so don't get your hopes up...

Thanks Jeff!

No need for hope - we have ahci now :)

(speaking of which, should I resend the patch without the RFC?)

Mark