Re: [PATCH v6 2/2] media: V3s: Add support for Allwinner CSI.

[Arnd Bergmann]

On Tue, Jan 30, 2018 at 8:54 AM, Maxime Ripard
<maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Jan 29, 2018 at 03:34:02PM +0100, Arnd Bergmann wrote:
>> On Mon, Jan 29, 2018 at 10:25 AM, Linus Walleij
>> <linus.walleij@xxxxxxxxxx> wrote:
>> > On Mon, Jan 29, 2018 at 9:25 AM, Maxime Ripard
>> > <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
>> >> On Sat, Jan 27, 2018 at 05:14:26PM +0100, Linus Walleij wrote:

>>
>> At one point we had discussed adding a 'dma-masters' property that
>> lists all the buses on which a device can be a dma master, and
>> the respective properties of those masters (iommu, coherency,
>> offset, ...).
>>
>> IIRC at the time we decided that we could live without that complexity,
>> but perhaps we cannot.
>
> Are you talking about this ?
> https://elixir.free-electrons.com/linux/latest/source/Documentation/devicetree/bindings/dma/dma.txt#L41
>
> It doesn't seem to be related to that issue to me. And in our
> particular cases, all the devices are DMA masters, the RAM is just
> mapped to another address.

No, that's not the one I was thinking of. The idea at the time was much
more generic, and not limited to dma engines. I don't recall the details,
but I think that Thierry was either involved or made the proposal at the
time.

       Arnd