Re: [PATCH v2 1/2] of/pci: add of_pci_dma_configure() update dma configuration

Will Deacon
2015-01-06T19:50:49Z

On Fri, Jan 02, 2015 at 10:33:53PM +0000, Murali Karicheri wrote:
> On 01/02/2015 03:45 PM, Rob Herring wrote:
> > On Fri, Jan 2, 2015 at 11:20 AM, Murali Karicheri<m-karicheri2@ti.com> wrote:
> >> On 12/26/2014 02:33 PM, Rob Herring wrote:
> >>> On Wed, Dec 24, 2014 at 4:11 PM, Murali Karicheri<m-karicheri2@ti.com>
> >>>> + coherent = of_dma_is_coherent(parent_np);
> >>>> + dev_dbg(dev, "device is%sdma coherent\n",
> >>>> + coherent ? " " : " not ");
> >>>> +
> >>>> + arch_setup_dma_ops(dev, dma_addr, size, NULL, coherent);
> >>>
> >>>
> >>> This is the same code as of_dma_configure. The only difference I see
> >>> is which node ptr is passed to of_dma_get_range. You need to make that
> >>> a function param of of_dma_configure.
> >>>
> >>> of_dma_configure also has iommu handling now. You will probably need
> >>> something similar for PCI in that you setup an iommu based on the root
> >>> bus DT properties.
> >>>
> >> Initially I had the same idea to re-use the existing function
> >> of_dma_configure() for this. I wanted to defer this until we have an
> >> agreement on the changes required for the subject functionality. My quick
> >> review of the code suggestio this would require additional API changes as
> >> below. I did a quick test of the changes and it works for Keystone, but need
> >> to be reviewed by everyone as I touch the IOMMU functionality here and I
> >> don't have a platform with IOMMU. Need test by someone to make sure I don't
> >> break anything.
> >
> > The IOMMU changes look trivial. We may want to address the comment in
> > of_iommu_configure about parent nodes. We should be sure these changes
> > work with how we would do searching parent nodes.
>
> I have no experience with IOMMU and may not offer much help here as I
> originally wrote above. Will Deacon has added this API and probably able
> to offer some help in this discussion.
>
> Will Deacon,
>
> Any comment?

Sorry for the delay; I'm still catching up on email after the Christmas
break, but I *will* get around to looking at this. If you have a new version
to post based on the comments from Rob and Arnd, feel free to send that and
I'll look at that instead.

Will