[PATCH v2 01/12] dt-bindings: media: qcom,venus: Add context bank subnodes to common schema

[Vikash Garodia]

The VPU issues DMA through several SMMU streams, and the hardware does
not give every stream the same addressable range. The non-pixel stream
is restricted to use 0-600MB of IOVA space, while the pixel stream can
address the full range:
    +-----------------------------------------------------------+
    | non-pixel stream addressable range (600 MB - 3.5 GB)      |
    | 0x25800000 - 0xe0000000                                   |
    +-----------------------------------------------------------+
    | pixel stream addressable range (0 - 3.5 GB)               |
    | 0x00000000 - 0xe0000000                                   |
    +-----------------------------------------------------------+
A single "iommus" property on the video-codec node puts every stream in
one IOMMU domain sharing one IOVA allocator, so nothing keeps a
non-pixel buffer inside the low 600 MB. Once an allocation lands below
that boundary the hardware faults, which shows up as unhandled SMMU page
faults and spontaneous reboots:
https://gitlab.freedesktop.org/drm/msm/-/work_items/100

Describe each stream as its own context bank subnode instead, so that
each can be associated with the IOVA range its stream can actually
reach. This limitation applies to every VPU generation, so add the
subnodes to the common schema rather than to each SoC schema
individually. "video-firmware" moves here from qcom,sc7180-venus.yaml
for the same reason; it is the same kind of node and was already
duplicated per-SoC.
Adding the subnodes requires two supporting properties on the parent
video-codec node:
- '#address-cells' and '#size-cells', both fixed at 2. These do not
   describe registers on the codec node. They set the cell widths
   used when a reserved-memory node names one of these subnodes in an
   "iommu-addresses" entry: of_translate_dma_region() reads the
   address/size cell counts from the parent of the phandle target, not
   from the reserved-memory node. Pinning both to 2 lets a subnode be
   referenced with a full 64-bit IOVA base and length, and keeps the
   encoding identical across SoCs, whose buses vary between 1 and 2
   cells.
- "dma-ranges", empty "dma-ranges" states the intended translation:
   the subnode DMA address space maps 1:1 into the parent's, so an IOVA
   reservation written against a subnode needs no offset applied.
   of_translate_one() treats an empty "dma-ranges" as exactly that
   identity mapping.

The parent's "iommus" is kept as an alternative via "oneOf", so
platforms that have not been converted to subnodes still validate. New
platforms should use the subnode form.

Fixes: 41661853ae8e ("arm64: dts: qcom: sm8550: add iris DT node")
Cc: stable@xxxxxxxxxxxxxxx
Tested-by: Daniel J Blueman <daniel@xxxxxxxxx>
Signed-off-by: Vikash Garodia <vikash.garodia@xxxxxxxxxxxxxxxx>
---
 .../bindings/media/qcom,sc7180-venus.yaml          | 15 -------
 .../bindings/media/qcom,venus-common.yaml          | 51 ++++++++++++++++++++++
 2 files changed, 51 insertions(+), 15 deletions(-)

diff --git a/Documentation/devicetree/bindings/media/qcom,sc7180-venus.yaml b/Documentation/devicetree/bindings/media/qcom,sc7180-venus.yaml
index b21bed314848480b82153e49602f0b19e08e7335..bfd8b1ad473128c974bce84639cb0aff59d8c2cc 100644
--- a/Documentation/devicetree/bindings/media/qcom,sc7180-venus.yaml
+++ b/Documentation/devicetree/bindings/media/qcom,sc7180-venus.yaml
@@ -91,21 +91,6 @@ properties:
     deprecated: true
     additionalProperties: false
 
-  video-firmware:
-    type: object
-    additionalProperties: false
-
-    description: |
-      Firmware subnode is needed when the platform does not
-      have TrustZone.
-
-    properties:
-      iommus:
-        maxItems: 1
-
-    required:
-      - iommus
-
 required:
   - compatible
   - power-domain-names
diff --git a/Documentation/devicetree/bindings/media/qcom,venus-common.yaml b/Documentation/devicetree/bindings/media/qcom,venus-common.yaml
index 59a3fde846d2196ab1e4588eb396012ba6860712..ccae41bed757bf3d9518cd4afe4565f043b45166 100644
--- a/Documentation/devicetree/bindings/media/qcom,venus-common.yaml
+++ b/Documentation/devicetree/bindings/media/qcom,venus-common.yaml
@@ -47,6 +47,50 @@ properties:
     minItems: 1
     maxItems: 4
 
+  dma-ranges: true
+
+  '#address-cells':
+    const: 2
+
+  '#size-cells':
+    const: 2
+
+  non-pixel:
+    type: object
+    description:
+      Context bank for VPU non-pixel buffers, including compressed and internal buffers.
+    properties:
+      iommus:
+        maxItems: 1
+      memory-region:
+        maxItems: 1
+    required:
+      - iommus
+      - memory-region
+    additionalProperties: false
+
+  pixel:
+    type: object
+    description:
+      Context bank for VPU pixel buffers containing uncompressed video data.
+    properties:
+      iommus:
+        maxItems: 1
+    required:
+      - iommus
+    additionalProperties: false
+
+  video-firmware:
+    type: object
+    description:
+      Context bank for the VPU firmware processing domain.
+    properties:
+      iommus:
+        maxItems: 1
+    required:
+      - iommus
+    additionalProperties: false
+
 required:
   - reg
   - clocks
@@ -55,4 +99,11 @@ required:
   - memory-region
   - power-domains
 
+oneOf:
+  - required:
+      - iommus
+  - required:
+      - non-pixel
+      - pixel
+
 additionalProperties: true

-- 
2.34.1