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SubjectRe: DAC960 in 2.5.38, with new changes

Ok, thanks for explaining!

At some point, I want to step back and look over the BIO and DMA code.
Possibly this will be my "project" for October :-)

On Tue, Sep 24, 2002 at 11:21:45AM -0700, David Mosberger wrote:
> >>>>> On Tue, 24 Sep 2002 10:28:43 -0700, Dave Olien <dmo@osdl.org> said:
>
> Dave> Hmm, interesting. A big part of what I'm doing to the driver
> Dave> right now is plugging in calls to the PCI DMA interfaces.
>
> That's fine (actually, it's more than that: it's great!).
>
> Dave> So unless the underlying implementation is aware of these
> Dave> platform limitations and "doing the right thing", I'm adding
> Dave> a bunch of bounce buffer activity for many ia64 platforms.
> Dave> That would be too bad.
>
> The idea is to do something along these lines:
>
> o Use PCA DMA interface for managing all DMA buffers.
>
> o If sizeof(dma_addr_t) > 4, turn on DAC mode and call
> pci_set_dma_mask(dev, MAX_ADDR), where MAX_ADDR is the maximum
> address that can be reached by the controller (i.e.,
> 0xffffffffffffffff for a truly 64-bit-capable PCI controller).
>
> This way, everything should work out correctly and with good
> performance on all imaginable platforms (ia64 with and without
> hardware I/O TLB, plain x86, x86 with >4GB RAM, SPARC64 with 32-bit
> dma_addr_t, etc.).
>
> --david
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