Messages in this thread | | | Date | Fri, 18 Jun 2004 15:48:42 -0400 | From | Jamey Hicks <> | Subject | Re: DMA API issues |
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Matt Porter wrote:
>On Fri, Jun 18, 2004 at 02:33:18PM -0400, Jamey Hicks wrote: > > >Yes, it can be cleaner, but it's not something I would say is >completely broken with the DMA API. It does provide a way to >make your device specific implementation, regardless of whether >it's managed ideally via a struct device pointer. Migrating to >dev->dma* sounds suspiciously like a 2.7ism. > > The DMA API is certainly not completely broken. Except for page_to_dma needing struct device the interface could be implemented with per-device dma operation implementations.
>>described, but there is already a good start towards that support in >>2.6. The other thing that might be needed is passing device to >> >> > >Where's that code? > > > arch/arm/common/dmabounce.c
>>page_to_dma so that device specific dma addresses can be constructed. >> >> > >A struct device argument to page_to_dma seems like a no brainer to be >included. > > > >>Deepak Saxena wrote a pretty good summary as part if the discussion >>about this issue on the linux-arm-kernel mailing list: >> >>http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-June/022796.html >> >> > >Ahh, ok. Deepak and I have discussed this idea F2F on a several >occassions, I recall he needed it for the small floating PCI window >he has to manage on the IXP* ports. It may help in some embedded >PPC areas as well. > > > >>I think I'm looking for something like the PARISC hppa_dma_ops but more >>generic: >> >>http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-June/022813.html >> >> > >I see that's somewhat like what David Brownell suggested before...a single >pointer to a set of dma ops from struct device. hppa_dma_ops translated >into a generic dma_ops entity with fields corresponding to existing >DMA API calls would be a good starting point. We can get rid of some >address translation hacks in a lot of custom embedded PPC drivers >with something like this. > > Yes, I think this would be generally useful.
Jamey
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