Re: [RFC][PATCH 1/3] dt-bindings: dma-buf: heaps: Describe CMA regions to be added to dmabuf heaps interface.

From
Rob Herring <hidden>
Date
2019-10-25 23:32:44
Also in
dri-devel, lkml
Reply to
John Stultz, 2019-10-25
On Fri, Oct 25, 2019 at 5:51 PM John Stultz [off-list ref] 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. ;)
quoted hunk ↗ jump to hunk
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Laura Abbott <redacted>
Cc: Benjamin Gaignard <redacted>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Liam Mark <redacted>
Cc: Pratik Patel <redacted>
Cc: Brian Starkey <Brian.Starkey@arm.com>
Cc: Andrew F. Davis <redacted>
Cc: Chenbo Feng <redacted>
Cc: Alistair Strachan <redacted>
Cc: Sandeep Patil <redacted>
Cc: Hridya Valsaraju <redacted>
Cc: <redacted>
Cc: <redacted>
Signed-off-by: John Stultz <redacted>
---
 .../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
Thread (7 messages) 7 messages, 3 authors, last reply 2019-10-30
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