[PATCH v2 2/5] dt-bindings: media: qcom,sc7280-venus: Add dma-coherent property

[Vishnu Reddy]

The venus video hardware on SC7280 is IO-coherent hardware: even though
the driver does dma_sync*() calls for the input and output buffers, the
venus node still needs to declare dma-coherent so that the DMA mapping
layer relies on this hardware level snooping to keep the CPU cache and
the DMA buffers in sync. This avoids the unnecessary cache clean or
invalidate operations performed by the dma_sync*() calls, which are not
required once hardware level snooping is enabled via dma-coherent.

Add the dma-coherent property to the venus node to describe this
hardware capability.

Fixes: 37613aee2179 ("arm64: dts: qcom: sc7280: Add venus DT node")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
Signed-off-by: Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>
---
 Documentation/devicetree/bindings/media/qcom,sc7280-venus.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/media/qcom,sc7280-venus.yaml b/Documentation/devicetree/bindings/media/qcom,sc7280-venus.yaml
index 9725fcb761dc..cc31f3ba7e7e 100644
--- a/Documentation/devicetree/bindings/media/qcom,sc7280-venus.yaml
+++ b/Documentation/devicetree/bindings/media/qcom,sc7280-venus.yaml
@@ -42,6 +42,8 @@ properties:
       - const: vcodec_core
       - const: vcodec_bus
 
+  dma-coherent: true
+
   iommus:
     maxItems: 1
 
@@ -85,6 +87,7 @@ properties:
 
 required:
   - compatible
+  - dma-coherent
   - power-domain-names
   - iommus
 
@@ -119,6 +122,8 @@ examples:
                         <&mmss_noc MASTER_VIDEO_P0 0 &mc_virt SLAVE_EBI1 0>;
         interconnect-names = "cpu-cfg", "video-mem";
 
+        dma-coherent;
+
         iommus = <&apps_smmu 0x2180 0x20>;
 
         memory-region = <&video_mem>;

-- 
2.34.1