Re: AHCI support Port Multiplier problem.

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 [off-list ref]
主旨: Re: AHCI support Port Multiplier problem.
收件者: "Luo Dislo" [off-list ref]
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:

quoted

I am using AHCI driver, when CONFIG_SATA_PMP is set

and the ahci

quoted

driver DOES NOT have AHCI_HFLAG_NO_PMP. Libata sends

Software Reset

quoted

with PMP=0xF, trying to detect if Port Multiplier

connected to the

quoted

port. Unfortunately, if I plugged in general Hard

drive, my

quoted

controller failed to identify the hard drive.

What I observed was that libata always sent Software

Reset with

quoted

PMP=0xF and I guessed expecting signature is

0x96690101. I think

quoted

libata should give up if the device does not return

the Port

quoted

Multiplier signature at the first time and take the

signature value

quoted

from device as the real device connnecting to the port

now.

quoted

What we said "support" PMP does not mean the port can

only connnect

quoted

to Port Multiplier. It might connect with hard drive

or ATAPI

quoted

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