Re: [PATCH] via82cxxx IDE: Support multiple controllers

From: Alan Cox
Date: Thu Oct 13 2005 - 06:17:31 EST

On Mer, 2005-10-12 at 18:52 +0100, Alan Cox wrote:
> On Mer, 2005-10-12 at 16:57 +0100, Daniel Drake wrote:
> > Uh, looks like the kernel just assumes 33mhz unless overriden by the user. Is
> > this assumption generally accurate?
> > If it is not, then there's probably no point displaying timing info...
> A small number of 486 systems use 25Mhz, some boards allow overclock at
> 37.5Mhz on the PCI. I've been looking at this the past couple of days
> for the libata via driver which I've been porting over and unfortunately
> having been through the Northbridge manuals I can find no way to ask the
> chipset what the PCI clock is set too.

Ok I found what seems to be a pattern for the early chipsets with 25MHz

If the bus speed of your 486 is 25Mhz the chipset is at 25MHz as is your
IDE (ie 486/25, DX2/50, 3/75 - not sure about 4/100 etc). Now does
anyone know how you find out if the CPU is 25MHz bus clocked on a 486 8)

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