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Subject[PATCH][highly-experimental] via-mwq (Was: Re: VIA acknowledges North Bridge bug...)
----- Original Message -----
From: "Calin A. Culianu" <>
To: "Petri Kaukasoina" <>
Cc: <>
Sent: Thursday, December 06, 2001 11:09 PM
Subject: Re: VIA acknowledges North Bridge bug (AKA Linux Kernel with Athlon

> Here is the webpage:
> This patch detects the 0305, 3099, 3102, and 3112 (KT133x, KT266x, VT8662,
> and KLE133) *only*. On these chipsets, it will patch register 55 in the
> Northbridge, which will supposedly switch off a Memory Write Queue timer.
> In the KT133A datasheet, register 55 is "reserved". But - yikes! - in the
> KT266, the documented MWQ register is register 95, not 55. Register 55
> contains unrelated DDR timing adjustments and could actually be dangerous
> to program. For this reason, I do not recommend installing this driver on
> the KT266x chipsets until VIA examines this issue. For now, use WPCREDIT
> and set bits 5, 6, and 7 to zero in register 95 instead."
> ----
> Clearly, we need to modify the via workaround patches to take into account
> the other via device id's (namely 3099, 3102, and 3112), and for each one
> change the appropriate register. Either register 55 or in the case of the
> kt266x, register 95. I am grepping through quirks.c right now and it
> seems this would be the correct file to modify.. any other suggestions on
> what file to modify?

I've (hastily) put these changes into "arch/i386/kernel/pci-pc.c" and had to
modify "include/linux/pci_ids.h" too.

The patch is included, but a warning: I have no VIA based computer that I
can test this on myself...

| Martin Eriksson <>
| MSc CSE student, department of Computing Science
| Umeå University, Sweden

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