Re: [PATCH v2 2/4] dt-bindings: dma: sf-pdma: add new compatible name

Rob Herring
2023-10-04T13:30:35Z

On Tue, Oct 03, 2023 at 09:52:13AM +0530, shravan chippa wrote:
> From: Shravan Chippa <shravan.chippa@microchip.com>
>
> Add new compatible name microchip,mpfs-pdma to support
> out of order dma transfers
>
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> Signed-off-by: Shravan Chippa <shravan.chippa@microchip.com>
> ---
> .../bindings/dma/sifive,fu540-c000-pdma.yaml | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml b/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
> index a1af0b906365..974467c4bacb 100644
> --- a/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
> +++ b/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
> @@ -27,10 +27,14 @@ allOf:
>
> properties:
> compatible:
> - items:
> - - enum:
> - - sifive,fu540-c000-pdma
> - - const: sifive,pdma0
> + oneOf:
> + - items:
> + - const: microchip,mpfs-pdma # Microchip out of order DMA transfer
> + - const: sifive,fu540-c000-pdma # Sifive in-order DMA transfer

This doesn't really make sense. microchip,mpfs-pdma is compatible with
sifive,fu540-c000-pdma and sifive,fu540-c000-pdma is compatible with
sifive,pdma0, but microchip,mpfs-pdma is not compatible with
sifive,pdma0? (Or replace "compatible with" with "a superset of")

Any fallback is only useful if an OS only understanding the fallback
will work with the h/w. Does this h/w work without the driver changes?

Rob