qla_wxyz pci_set_mwi question

Benjamin Herrenschmidt benh at kernel.crashing.org
Fri Apr 13 12:43:43 EST 2007

> Willy was referring to this from include/asm-powerpc/pci.h:
> #ifdef CONFIG_PPC64
> /*
>  * We want to avoid touching the cacheline size or MWI bit.
>  * pSeries firmware sets the cacheline size (which is not the cpu cacheline
>  * size in all cases) and hardware treats MWI the same as memory write.
>  */
> which makes pci_set_mwi() do nothing other than return 0;

Interesting... I think I missed that we had that bit for some time :-)

Well, I suppose that on pSeries and probably pmac too, the firmware will
set the MWI bit for us anyway, but that's a bit dodgy to apply that to
all ppc64... they aren't all pSeries.

I'll have to look into that again one of these days.


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