On 12/15/2009 06:03 PM, Krzysztof Halasa wrote:
Tejun Heo<tj@xxxxxxxxxx> writes:
Hmmm... Given that there are some platforms which have problem with
mmio and sil3112/4 can do everything via io accesses, it would be nice
to generalize this so that there's CONFIG_SATA_SIL_NO_MMIO which is
selected by affected platforms. Are you interested in doing it?
Unfortunately I no longer have access to that SIL3512 miniPCI card so
I wouln't be able to test on IXP425. Perhaps it's not a problem, testing
on i386 (probably with disabled MMIO BAR) should be enough.
OTOH IIRC SIL3x12 needs to use the MMIO write to start BM DMA, otherwise
the AT-style 64 KB limits apply. I think IXP4xx would benefit from only
ioread8() going through normal IO.
Do you know what platforms have the MMIO problems? What kind of problems
are there, inability to use MMIO at all? (IXP4xx can't do 8/16-bit MMIO
reads).
The inability to do 8/16-bit MMIO reads are a repeated sticking point
with embedded scenarios. That's it.
I keep meaning to give the docs a hard look, and see if we can combine
multiple taskfile register reads/writes into a single 32-bit one. That
would solve all these problems, without having to resort to the use of
standard BARs.
Jeff
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