Re: which bus_dmamap_sync() ?

[David Young <dyoung%pobox.com@localhost>]

On Fri, Jun 20, 2008 at 07:44:15PM +0200, Manuel Bouyer wrote:
> Hi,
> can anyone tell me what bus_dmamap_sync() function port-macppc is using for
> its PCI bus ? I've been looking at arch/macppc/ and arch/powerpc/ and
> my conclusion is that bus_dmamap_sync() is a nop on port-macppc
> (_dmamap_sync being NULL). Is this right ?

It is a nop, but strictly speaking, *no* bus_dmamap_sync() for PCI bus
should be a nop, because that ignores the presence of buffers in the
bus bridges.  NetBSD ordinarily lucks out because most drivers have
read an interrupt status register on the bus master prior to calling
bus_dmamap_sync().  The register read has the side-effect of flushing
buffers to RAM.

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933 ext 24