On Tue, Nov 17, 2020 at 10:19 AM Minchan Kim <minchan@xxxxxxxxxx> wrote: > > From: Hyesoo Yu <hyesoo.yu@xxxxxxxxxxx> > > Document devicetree binding for chunk heap on dma heap framework > > Signed-off-by: Hyesoo Yu <hyesoo.yu@xxxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > --- > .../bindings/dma-buf/chunk_heap.yaml | 52 +++++++++++++++++++ > 1 file changed, 52 insertions(+) > create mode 100644 Documentation/devicetree/bindings/dma-buf/chunk_heap.yaml > > diff --git a/Documentation/devicetree/bindings/dma-buf/chunk_heap.yaml b/Documentation/devicetree/bindings/dma-buf/chunk_heap.yaml > new file mode 100644 > index 000000000000..f382bee02778 > --- /dev/null > +++ b/Documentation/devicetree/bindings/dma-buf/chunk_heap.yaml > @@ -0,0 +1,52 @@ > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/dma-buf/chunk_heap.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Device tree binding for chunk heap on DMA HEAP FRAMEWORK > + > +maintainers: > + - Sumit Semwal <sumit.semwal@xxxxxxxxxx> > + > +description: | > + The chunk heap is backed by the Contiguous Memory Allocator (CMA) and > + allocates the buffers that are made up to a list of fixed size chunks > + taken from CMA. Chunk sizes are configurated when the heaps are created. > + > +properties: > + compatible: > + enum: > + - dma_heap,chunk > + > + memory-region: > + maxItems: 1 > + > + alignment: > + maxItems: 1 > + > +required: > + - compatible > + - memory-region > + - alignment > + > +additionalProperties: false > + > +examples: > + - | > + reserved-memory { > + #address-cells = <2>; > + #size-cells = <1>; > + > + chunk_memory: chunk_memory { > + compatible = "shared-dma-pool"; > + reusable; > + size = <0x10000000>; > + }; > + }; > + > + chunk_default_heap: chunk_default_heap { > + compatible = "dma_heap,chunk"; > + memory-region = <&chunk_memory>; > + alignment = <0x10000>; > + }; So I suspect Rob will push back on this as he has for other dt bindings related to ion/dmabuf heaps (I tried to push a similar solution to exporting multiple CMA areas via dmabuf heaps). The proposal he seemed to like best was having an in-kernel function that a driver would call to initialize the heap (associated with the CMA region the driver is interested in). Similar to Kunihiko Hayashi's patch here: - https://lore.kernel.org/lkml/1594948208-4739-1-git-send-email-hayashi.kunihiko@xxxxxxxxxxxxx/ The one sticking point for that patch (which I think is a good one), is that we don't have any in-tree users, so it couldn't be merged yet. A similar approach might be good here, but again we probably need to have at least one in-tree user which could call such a registration function. thanks -john
