Re: AHCI support Port Multiplier problem.

[Luo Dislo <dislo_b_j@yahoo.com.tw>]

Hello,

This is my company(Faraday) implemented AHCI SATA controller. Our 
controller is not located at PCI bus, but AHB bus(ARM based platform).

However, I modify Linux kernel builtin AHCI driver(ahci.c) to replace
the PCI related code by using platform bus. Just pretty similar way 
with drivers/ata/ahci_platform.c (Kernel 2.6.35).

I think the problem happens because libata does not give up, keep on 
expecting the Port Multiplier Signature when we set CONFIG_SATA_PMP 
to 1. 

I know how to fix this problem, just add AHCI_HFLAG_NO_PMP to AHCI_HFLAGS when I connect hard drive to the controller. Meanwhile, when I want to connect the Port Muliplier to my controller, I need to remove AHCI_HFLAG_NO_PMP from AHCI_HFLAGS. 

I don't think this is a good solution because I have to compile two version of my code. It does not make sense. We set CONFIG_SATA_PMP to 1 and inside the driver code DOES NOT have AHCI_HFLAG_NO_PMP just means that controller support Port Multiplier but the device connecting to the port might be others type.



Regards,

Dislo


 

--- 11/1/8 (六)，Tejun Heo <tj@kernel.org> 寫道：

> 寄件者: Tejun Heo <tj@kernel.org>
> 主旨: Re: AHCI support Port Multiplier problem.
> 收件者: "Luo Dislo" <dislo_b_j@yahoo.com.tw>
> 副本: jgarzik@pobox.com, linux-ide@vger.kernel.org
> 日期: 2011年1月8日,六,上午5:25
> Hello,
> 
> On Fri, Jan 07, 2011 at 10:55:14AM +0800, Luo Dislo wrote:
> > I am using AHCI driver, when CONFIG_SATA_PMP is set
> and the ahci
> > driver DOES NOT have AHCI_HFLAG_NO_PMP. Libata sends
> Software Reset
> > with PMP=0xF, trying to detect if Port Multiplier
> connected to the
> > port. Unfortunately, if I plugged in general Hard
> drive, my
> > controller failed to identify the hard drive.
> > 
> > What I observed was that libata always sent Software
> Reset with
> > PMP=0xF and I guessed expecting signature is
> 0x96690101. I think
> > libata should give up if the device does not return
> the Port
> > Multiplier signature at the first time and take the
> signature value
> > from device as the real device connnecting to the port
> now.
> >
> > What we said "support" PMP does not mean the port can
> only connnect
> > to Port Multiplier. It might connect with hard drive
> or ATAPI
> > device.
> 
> Which controller is this?  Can you please post the
> output of "lspci
> -nn"?  SB600 had this problem and needed workaround
> but later SBs
> fixed it.  Looks like someone else screwed up
> similarly.
> 
> Thanks.
> 
> -- 
> tejun
>