[PATCH 2/4] dt-bindings: mmc: spacemit,sdhci: Add tx delay property

[Conor Dooley]

On Wed, Sep 02, 2026 at 07:03:13AM +0000, Yixun Lan wrote:
> From: Long Wan <long.wan at linux.spacemit.com>
> 
> Introduce a vendor specific property to configure the step count of TX
> delay line which should be applied before RX tuning, compensating for
> board level trace differences. The TX delay line result comes from test
> out of real board which vary from different hardware layout.
> 
> Signed-off-by: Long Wan <long.wan at linux.spacemit.com>
> Signed-off-by: Yixun Lan <dlan at kernel.org>

Everyone seems to have their own custom delays, so what's another..
Acked-by: Conor Dooley <conor.dooley at microchip.com>
pw-bot: not-applicable

> ---
>  Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml b/Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml
> index f35bf7ce08dd..3399a2d076dc 100644
> --- a/Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml
> +++ b/Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml
> @@ -63,6 +63,16 @@ properties:
>    pinctrl-1:
>      description: Optional pinctrl state for 1.8V UHS operation with "uhs" name
>  
> +  spacemit,tx-delay:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 255
> +    description:
> +      TX delay line setting applied before RX tuning, compensating for
> +      board level trace differences. This is a delay line step count with
> +      no fixed time-per-step conversion; determined empirically per board
> +      specific, used on SD/SDIO hosts.
> +
>  required:
>    - compatible
>    - reg
> 
> -- 
> 2.55.0
> 
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