Re: Weird PCI problem

Rogier Wolff (R.E.Wolff@BitWizard.nl)
Sat, 17 Apr 1999 11:55:33 +0200 (MEST)

Gerard Roudier wrote:
> If you can do that, then, I will recommend you to do at least:
>
> - Read this base address register
> - Warn if any of bit 1, 2 or 3 is set.
> - Mask all the bits that should have read zero (bit 0,1,2,3)
> - Rewrite this base address register
> - Read it again and warn if any bit 0, 1, 2 or 3 is still set.

In my opinion that last one should be "bail out if any of the
addressing type bits is still set".

The PLX (which I understand is the PCI bridge for the card) is capable
of mapping stuff into IO space as well as into memory space. It will
simply do whatever the bit is set at. You're supposed to program the
eeprom in such a way that the bit becomes read-only, but it is
certainly writeable in hardware, and the device will honour whatever
it is set at.

Telling the chip you want a 64k IOmapped window is probably going to
crash the machine sooner or later.

Roger.

-- 
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
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