Re: Acard ATP8620 2SATA / 1 IDE driver - AHCI.C Nov082007

["jameshsu" <jameshsu@acard.com>]

Jeff,

First, appreciate for taking few minutes to answer my short question:

1) How is the status of ACARD Linux SATA driver after spec studying??.
Any progress and any qustion/help needed from Acard, esp., AHCI support??
If you have draft open source(driver) now, do you mind to share with us!
Please advise! Thanks!

Best regards & happy holiday season!

James
----- Original Message -----
From: Jeff Garzik
To: jameshsu
Cc: Jason Wu ; LaurenceWu ; Andrew Morton ; IDE/ATA development list ;
tytso@us.ibm.com ; Matti Aarnio ; James Bottomley ; Daniel Weng
Sent: Friday, November 09, 2007 12:22 AM
Subject: Re: Acard ATP8620 2SATA / 1 IDE driver - AHCI.C Nov082007


On Thu, Nov 08, 2007 at 07:34:22PM +0800, jameshsu wrote:
> From: LaurenceWu

> We didn't study about ata/ahci.c, but it should be based on AHCI1.0 or 1.1
> spec. That is, NO P.M. FIS base switching, but supports both non-NCQ and
NCQ
> protocols.
>
> For NCQ or nonNCQ, 8620 is very AHCI-like, although not fully compatible,
> programmer can easily modify standard ahci.c
> for 8620. The main differences between 8620 and AHCI are :
>
> 1. PRD table format changed, (please compare AHCI 1.x section 4.2.3.3 and
> 8620 datasheet section 7.3), 'I' bit in 8620 is defined as 'EOT' and NO
> PRDTL value are available in the
>     Command List Structure.
>
> 2. For NCQ transfer, PxIS bit 3(SDBS) is changed. ATP8620 add the Reg_144h
> to accumulate 32 Sactive bits in each SDB FIS.
>     The Reg_144h is RWC and all its 32 bits are 'ORed'  to form the PxIS
> bit3 and interrupt, if PxIE bit 3 enabled.
>
> Yes.  Modifying the ata/ahci.c is OK to support atp8620.

This is good information, thanks.

After studying the datasheet I also noted a couple differences:

1) Port Multiplier support appears different from standard AHCI.

2) This chip includes target mode support.  Very nice, well done!
I hope that standard AHCI eventually supports this nice feature!

Jeff