Re: ASMedia ASM1166/ASM1064 port restrictions will break cards with port-multipliers

[Niklas Cassel <cassel@kernel.org>]

Hello Hans,

On Fri, Mar 15, 2024 at 04:01:07PM +0100, Hans de Goede wrote:
> > 
> > If they only claimed that the HBA supported PMP, the Linux device
> > driver would try to enumerate the devices behind the PMP according
> > to the standard.
> > 
> > See AHCI 1.3.1, section 9.2 Port Multiplier Enumeration.
> > Or
> > SATA-IO - Port Multiplier 1.0, 7.4.2 Device Enumeration.
> > 
> > The PMP standard also describes how you read the device and vendor
> > ID of the PMP.
> > 
> > 
> > Right now, they AMedia? seem to have their own home-made PMP implementation.
> 
> Ah, ok so I think you did see my reply? Checking if we can ignore
> the builtin PMP support and uses Linux PMP support instead is
> indeed an option.

Yes, I saw your reply.

I wouldn't call it "Linux PMP support", I would simply call it "PMP",
since how you enumerate a PMP is decribed in AHCI and SATA-IO specs.

The "builtin PMP support" is not PMP, since it doesn't follow the specs.
I would rather call it "non-standard vendor extension" or "pseudo-PMP".


> I think we should still merge the revert / dropping of the quirk
> while we figure this out though, because not finding people's disks
> anymore is a clear regression.

I was hoping that someone could try the patch I sent out on Thursday,
which sets the PMP supported bit in the CAP register, as that could
potentially solve both problems here.

I guess if no one has tested it by Monday or Tuesday, we will have
no choice but to revert.


Kind regards,
Niklas