On Feb 6, 2008, at 7:26 PM, Benjamin Herrenschmidt wrote: > > On Wed, 2008-02-06 at 18:32 -0600, Becky Bruce wrote: >> >> I've been looking at converting 32-bit powerpc's DMA code over to the >> 64-bit method, where there is a dma_ops structure inside archdata >> that tells us which operations a device should use for DMA. I'll be >> needing this shortly because I need to implement swiotlb to deal with >> PCI and large amounts of RAM on 32-bit systems that support 36-bit >> physical addressing. (Yes, I know. Fun for me. Woohoo.) >> >> Anyway, I have an initial booting first pass, and wanted to get some >> feedback. What I've done at this point is to make dma_64 common >> to both >> architectures (will rename it when I send a real patch...). The >> dma_direct_* functions have been changed to work on both 32/64, >> and the >> old dma_* functionality in dma-mapping.h has been removed. For >> now, to >> avoid whacking on every 32-bit platform, the get_dma_ops() >> function has >> been changed to return &dma_direct_ops if the device pointer >> exists but >> the dma_ops field is NULL. I'm not sure if this needs to be >> ifdef'd for >> 64-bit? > > I'd prefer so yes.
Ok. I'll put that in, but I'd like to understand why it's necessary.... > >> I've copied a bit of code over from pci_64.c into pci_common.c - >> some of >> it isn't in use yet but will be once I start doing actual setup in >> the >> platform code. pcibios_setup_new_device() becomes common as well. > > Cool ! > >> I've >> also temporarily hacked the 32-bit code to set archdata.dma_data to >> PCI_DRAM_OFFSET, so we can eliminate the use of virt_to_bus() and >> instead >> use the 64-bit method, which gets rid of some ugly ifdefs in the >> dma code. > > Ok. > >> That's really about it - the preliminary patch is below - clearly >> it will >> need some cleanup, but I wanted to post early and often. Any >> feedback or >> suggestions on cleaning this up are greatly appreciated. > > I'll have a look asap, thanks for doing this ! > Heh, don't thank me until you've looked at it :) Another thing that has to be done here is that I will need to audit all the driver code for places where the dev pointer passed to dma_alloc_coherent() and friends is NULL. I've already fixed the gianfar driver locally, but I expect there are a pile of them. If you have any other suggestions for dealing with this, speak up. Cheers, B _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
