DMA3 maximum burst length (in unit of beat) may be restricted depending on bus interconnect. As mentionned in STM32MP2 reference manual [1], "the maximum allowed AXI burst length is 16. The user must set [S|D]BL_1 lower or equal to 15 if the Source/Destination allocated port is AXI (if [S|D]AP=0)". Introduce st,axi-max-burst-len. If used, it will clamp the burst length to that value if AXI port is used, if not, the maximum burst length value supported by DMA3 is used. [1] https://www.st.com/resource/en/reference_manual/rm0457-stm32mp2325xx-advanced-armbased-3264bit-mpus-stmicroelectronics.pdf Signed-off-by: Amelie Delaunay <amelie.delaunay@xxxxxxxxxxx> --- .../devicetree/bindings/dma/stm32/st,stm32-dma3.yaml | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml b/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml index 38c30271f732e0c8da48199a224a88bb647eeca7..90ad70bb24eb790afe72bf2085478fa4cec60b94 100644 --- a/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml +++ b/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml @@ -51,6 +51,16 @@ properties: power-domains: maxItems: 1 + st,axi-max-burst-len: + description: | + Restrict AXI burst length in unit of beat by value specified in this property. + The value specified in this property is clamped to the maximum burst length supported by DMA3. + If this property is missing, the maximum burst length supported by DMA3 is used. + $ref: /schemas/types.yaml#/definitions/uint32 + minimum: 1 + maximum: 256 + default: 64 + "#dma-cells": const: 3 description: | @@ -137,5 +147,6 @@ examples: <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>; clocks = <&rcc CK_BUS_HPDMA1>; #dma-cells = <3>; + st,axi-max-burst-len = <16>; }; ... -- 2.25.1
