Cannot detect SATA disks w/ CONFIG_SATA_PMP w/o actually using SATA multiplier

[mkl0301@gmail.com (Lin Mac)]

2010/12/2 Tejun Heo <htejun@gmail.com>:
> Hello,
>
> On 12/02/2010 11:23 AM, Lin Mac wrote:
>>> One thing which could be possible is that the controller stashes the
>>> result code for the PMP aware SRST according to the PMP number instead
>>> of the usual place, so the driver can't see it. ?In that case, the
>>> driver can be modified to check both places I suppose but if the
>>> hardware can be fixed, that would be great.
>> the usual place, I presume you mean PxTFD+PxSIG.
>> I've check RFIS of received FIS structure after softreset failed and
>> nothing there. (UFIS neither)
>> Is there any other suspect to check?
> Have you checked all PxTFDs? ?It could be that the controller is
> saving it in the wrong slot.
No, they are not there.

>> My situation is that device is sending D2H Reg FIS, but controller is
>> not reflecting it on PxTFD, PxSIG, or RFIS of received FIS
>> structure.With the patch I sent, it seems the controller receives D2H
>> Reg FIS of the same PMP setting of the previous sent H2D Reg FIS, and
>> drop the different one.
>
> If the controller is dropping the D2H Reg FIS altogether, it'll
> probably need more intricate workaround. ?:-(
>
>> The AHCI controller I used is AHCI v1.1 compatible, command-based switching.
>>
>> In SATA spec (rev2.6) 16.7.1, it says:
>>
>> A host controller may support command-based switching by implementing
>> the Port Multiplier Port (PMP) field in the SControl register as
>> detailed in section 14.1.3.In order to use this mechanism, host
>> software would set the PMP field appropriately before issuing a
>> command to a device conected to the Port Multiplier. (...) Note that
>> the PMP field shall be set to the control port when host software
>> issues commands to the Port Multiplier itself.
>> --
>>
>> In AHCI spec, the PMP field of PxSCTL "is not used by AHCI".Does it
>> implies AHCI would set it and software doesn't need to do anything?
>>
>> 13.13.4.1 Port Multiplier Discovery
>> If ?a device is present, the host issues a software reset with the PM
>> Port field set ?to the control port. The host checks the signature
>> value returned and if....
>> --
>>
>> SATA spec didn't says what to do IF it received a data with PMP
>> setting doesn't match it's current setting (did it?). While 13.13.4.1
>> only implies the host should receive the signature successfully, even
>> if it is of different PMP setting.
>
> The probing sequence is described somewhere in the ahci spec and I'm
> fairly sure the dropping behavior you're describing is out of spec.
> You'll need to find a way to reliably distinguish a PMP device and
> then probably implement the workaround in custom hardreset or
> softreset method for the specific controller.
I have resent the patch which retry ahci_do_softreset again with pmp=0
if pmp=15 failed.
Thanks a lot for the help.

Best Regards,
Mac Lin