On Fri, Oct 25, 2019 at 5:51 PM John Stultz <[email protected]> wrote:
>
> This binding specifies which CMA regions should be added to the
> dmabuf heaps interface.

Is this an ION DT binding in disguise? I thought I killed that. ;)

>
> Cc: Rob Herring <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Laura Abbott <[email protected]>
> Cc: Benjamin Gaignard <[email protected]>
> Cc: Sumit Semwal <[email protected]>
> Cc: Liam Mark <[email protected]>
> Cc: Pratik Patel <[email protected]>
> Cc: Brian Starkey <[email protected]>
> Cc: Andrew F. Davis <[email protected]>
> Cc: Chenbo Feng <[email protected]>
> Cc: Alistair Strachan <[email protected]>
> Cc: Sandeep Patil <[email protected]>
> Cc: Hridya Valsaraju <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: John Stultz <[email protected]>
> ---
>  .../bindings/dma/dmabuf-heap-cma.txt          | 31 +++++++++++++++++++
>  1 file changed, 31 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/dmabuf-heap-cma.txt
>
> diff --git a/Documentation/devicetree/bindings/dma/dmabuf-heap-cma.txt 
> b/Documentation/devicetree/bindings/dma/dmabuf-heap-cma.txt
> new file mode 100644
> index 000000000000..bde7b1f1c269
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/dmabuf-heap-cma.txt
> @@ -0,0 +1,31 @@
> +* DMA-BUF CMA Heap
> +
> +Specifies a CMA region that should be added to the dma-buf heaps
> +interface.
> +
> +Required properties:
> +- compatible: Must be "dmabuf-heap-cma"
> +- memory-region: phandle to a CMA reserved memory node
> +
> +Example:
> +This example has a camera CMA node in reserved memory, which is then
> +referenced by the dmabuf-heap-cma node.
> +
> +
> +       reserved-memory {
> +               #address-cells = <2>;
> +               #size-cells = <2>;
> +               ranges;
> +               ...
> +               cma_camera: cma-camera {
> +                       compatible = "shared-dma-pool";
> +                       reg = <0x0 0x24C00000 0x0 0x4000000>;
> +                       reusable;
> +               };
> +               ...
> +       };
> +
> +       cma_heap {
> +               compatible = "dmabuf-heap-cma";
> +               memory-region = <&cma_camera>;

Why the indirection here? Can't you just add a flag property to
reserved-memory nodes like we do to flag CMA nodes?

As I suspected, it's because in patch 2 you're just abusing DT to
instantiate platform devices. We already support binding drivers to
reserved-memory nodes directly.

Rob
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