New API for non cache coherent ppc cpu's

Paul Mackerras paulus at
Fri Nov 23 12:32:50 EST 2001

Dan Malek writes:

> That's exactly what it is.  We are not creating a new API, and it shouldn't
> have been described as such.

OK... Armin's message wasn't exactly clear... :)

> They do.  Recently a pci_sync_page was added for some reason (because

To go with pci_map_page and pci_unmap_page.  These give you the
ability to do DMA to highmem pages without using bounce buffers.

> > If you're talking about non-PCI devices, use the pci DMA API but just
> > pass NULL for the dev (we need to make sure that will work ok on the
> > non-cache-coherent cpus).
> Ummm....I don't normally do this because using these functions requires
> the CONFIG_PCI option, which isn't supported or has bad effects when
> requested on processors that don't have PCI.  For non-PCI devices,
> I call the consistent_* functions, which other architectures support
> and do as well.  So, we kind of have a common interface here for non-PCI
> devices as well.

My preference would be to make the one set of functions work
everywhere.  OTOH these non-PCI devices you're talking about are
presumably very specific to PPC embedded chips so maybe it doesn't
matter so much.


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