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

Murali Karicheri m-karicheri2 at ti.com
Tue Jan 6 13:08:43 PST 2015

On 01/06/2015 02:50 PM, Will Deacon wrote:
> 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 at 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 at 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

I will be posting v3 of the patch tomorrow and you can review that.



Murali Karicheri
Linux Kernel, Texas Instruments

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