On Thu, Oct 10, 2024 at 04:27:56PM +0200, Amelie Delaunay wrote: > 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)". This should be implied by the SoC specific compatible. > > 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 >
