Broken PCI bridges (was Re: outrigger motherboard and i840 locking at PCI Probing)

From: Derek Fawcus (dfawcus@cisco.com)
Date: Mon Jul 31 2000 - 20:24:03 EST


On Mon, Jul 31, 2000 at 10:59:12PM +0100, Alan Cox wrote:
>
> > PCI Interface Chips that support complex devices like a 'Mass storage
> > controller' can be filthy with bugs, however the bridge chip itself
> > either works or it doesn't.
>
> Wrong.
>
> Some examples
>
> o SIS 486 chipsets. PCI dma to another PCI target directly doesnt work
> o VIA VP* PCI/ISA bridge gets ISA bus mastering DMA disable wrong and
> locks the board
> o Triton you have to turn off streaming and peer concurrency for some
> configurations

A tricky one I've been playing around with:

Toshiba docking station PCI-PCI bridge (Vendor id=1179. Device id=0609)

It works but the range registers (IO limit & base, Memory limit & base)
always return 0 on read. Other than that it seems to function.
  
However it sure confuses the 2.4 kernel! The only way I can see to deal
with this is to try and infer the values from those ranges assigned to
other devices. But at the moment I'm using a gross hack.

DF

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