Re: [RFC] IDE 80-core cable detect - chipset-specific code to over-ride eighty_ninty_three()

[Willy Tarreau]

On Sat, Feb 07, 2004 at 05:00:18PM +1100, Athol Mullen wrote:
> (Don't CC.  I read lkml via linux.kernel newsgroup.)

(sorry, it was easier to hit 'g' in mutt...)

> Specific to parallel IDE with UDMA.  Relates to code that is the same from 
> 2.4.22 to 2.6.1.
> 
> After looking through the Intel specs for the ICH5, I discovered that they 
> specify that the BIOS is supposed to initialise bit flags for the presence of 
> 80-core ribbon for each drive.  According to Intel, the OS is supposed to 
> rely upon those flags in preference to the word-93 bit.  This appears to 
> cover all ICH chipsets capable of UDMA modes that require 80-core cabling, 
> and works on both the ICH4 and ICH5 I have here.

that could explain why I recently discovered that a 2.4.25-rc1 on a supermicro
MB with ICH5 was limiting hda and hdb to 30 MB/s at UDMA33 while an old 2.4.20
+ many patches including IDE gave me about 64 MB/s at UDMA100.

I can hack piix_ratemask() to test if the limit goes away.

> I'm not certain exactly how this would be implemented, but I'd like to see 
> eighty_ninty_three() check for chipset-specific detection code, and use the 
> existing word93 validation otherwise.
> 
> I have written and tested code for the intel ICH chipsets, but can't post a 
> patch until I know where to stick it.  :-)

well, why not in piix:piix_ratemask() around line 315 ?

Cheers,
Willy

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