Re: [PATCH v1] dt-bindings: dma: st-stm32-dmamux: Add description for dma-cell values

[Amelie Delaunay]

On 12/5/24 17:09, Krzysztof Kozlowski wrote:
> On 05/12/2024 17:07, Ken Sloat wrote:
> > > > + 1. The mux input number/line for the request
> > > > + 2. Bitfield representing DMA channel configuration that is passed
> > > > + to the real DMA controller
> > > > + 3. Bitfield representing device dependent DMA features passed to
> > > > + the real DMA controller
> > > > +
> > > > + For bitfield definitions of cells 2 and 3, see the associated
> > > > + bindings doc for the actual DMA controller the mux is connected
> > >
> > > This does not sound right. This is the binding for DMA controller, so
> > > you are saying "please look at itself". I suggest to drop this as well.
> >
> > While logically it is the DMA controller, this doc is specifically for
> > the mux - the DMA controller has its own driver and binding docs in
> > Documentation/devicetree/bindings/dma/stm32/st,stm32-dma.yaml
> >
> > I can reference st,stm32-dma.yaml directly, but I was unsure if this
> > mux IP was used with another DMA controller from ST on a different
> > SoC.
> >
> > What do you suggest here?
>
> Thanks for explanation, I think it is fine.
>
> Best regards,
> Krzysztof

This description was lost when STM32 DMAMUX binding txt file was 
converted to yaml:
0b7c446fa9f7 ("dt-bindings: dma: Convert stm32 DMAMUX bindings to 
json-schema")

-- #dma-cells:	Should be set to <3>.
-		First parameter is request line number.
-		Second is DMA channel configuration
-		Third is Fifo threshold
-		For more details about the three cells, please see
-		stm32-dma.txt documentation binding file


stm32-dmamux exclusively muxes stm32-dma channels. It is not used with 
other ST DMA controllers (STM32 MDMA, STM32 DMA3).

So it is fine to refer to st,stm32-dma.yaml.

Regards,
Amelie