Re: sata_nv + ADMA + Samsung disk problem

[Robert Hancock]

Benjamin Herrenschmidt wrote:
> > Another thing about the PacDigi core:  one has to be very careful
> > to avoid sequential accesses to sequential PCI locations when
> > programming the chip -- it cannot handle merged register writes.
> >
> > So for any group of sequentially laid out registers, the code has
> > to ensure it never writes two adjacent registers in sequence..
>
> Ugh ? Write combining isn't permitted on normal registers afaik...
>
> Ben.

Byte merging can be done by the chipset on MMIO writes (merging multiple 
8 or 16-bit writes into a single 32-bit cycle).
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