Re: eepro100 (PCI ID 82820) lockups/failure

[Richard B. Johnson]

On Tue, 7 Aug 2001, Andrey Savochkin wrote:
[SNIPPED...]

> 
> However, for this particular case I'm interested about a loop like
> 	while((a = readb(reg)) && --count >= 0);
> I wonder if there are circumstances in which the repeated read's can return
> "cached" values or whatever, so that the loop will result in significantly less
> number of bus cycles than it's supposed?
> My understanding is that there shouldn't be such.
> 
> Best regards
> 		Andrey

You should have obtained access to the PCI address space by using
ioremap_nocache(). If so, every read will go to the bus. However,
what is actually read will be long-words so, if the device assumes
something else, its broken. FYI, some ISA word-addressed boards
have been "converted" to PCI by glueing on a PCI interface chip.
They require some strange hacks to work, like reading a byte register
by using the lowest long-word-aligned address that will contain that
byte and shifting the result.

Cheers,
Dick Johnson

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