Re: [PATCH 2/3] spi: dt-bindings: Add num-cs property for mpfs-spi

From: Conor Dooley
Date: Fri May 03 2024 - 06:40:32 EST


On Thu, May 02, 2024 at 03:34:09PM +0100, Prajna Rajendra Kumar wrote:
> The PolarFire SoC SPI controller supports multiple chip selects,but in
> the MSS, only one CS line is physically wired. To reflect this hardware
> limitation in the device tree, the binding enforces that the 'num-cs'
> property defaults to 1 and cannot exceed 1 unless additional
> chip select lines are explicitly defined using GPIO descriptors.
>
> Fixes: 2da187304e55 ("spi: add bindings for microchip mpfs spi")
> Signed-off-by: Prajna Rajendra Kumar <prajna.rajendrakumar@xxxxxxxxxxxxx>
> ---
> .../bindings/spi/microchip,mpfs-spi.yaml | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml b/Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml
> index 74a817cc7d94..19951951fdd6 100644
> --- a/Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml
> +++ b/Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml
> @@ -13,9 +13,6 @@ description:
> maintainers:
> - Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
>
> -allOf:
> - - $ref: spi-controller.yaml#
> -
> properties:
> compatible:
> oneOf:
> @@ -43,6 +40,22 @@ required:
> - interrupts
> - clocks
>
> +allOf:
> + - $ref: spi-controller.yaml#
> + - if:
> + properties:
> + compatible:
> + contains:
> + const: microchip,mpfs-spi
> + not:
> + required:
> + - cs-gpios
> + then:
> + properties:
> + num-cs:
> + default: 1
> + maximum: 1

I think this isn't quite right actually. The default for num-cs should
be 1, regardless of whether cs-gpios are used or not, only the maximum
is affected by using GPIOs for chip select.

> +
> unevaluatedProperties: false
>
> examples:
> --
> 2.25.1
>

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