Subject: Re: [PATCH v2 3/6] dt-bindings: mmc: fsl-imx-esdhc: add fsl,broken-auto-tuning binding

From: Rob Herring <[email-masked]>
Date: Wed, 18 Aug 2021 13:48:52 -0500

On Wed, Aug 18, 2021 at 07:16:52PM +0800, [email-masked] wrote:
> From: Haibo Chen <[email-masked]>
> 
> Add a new fsl,broken-auto-tuning binding for sdio devices. When sdio
> device support sdio interrupt, need to use this property to disable
> auto-tuning. Auto-tuning circuit is conflict with sdio interrupt.
> 
> Signed-off-by: Haibo Chen <[email-masked]>
> ---
>  Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml
> index b5baf439fbac..d7c8e5880473 100644
> --- a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml
> +++ b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml
> @@ -93,6 +93,15 @@ properties:
>        tuning step can't find the proper delay window within limited tuning retries.
>      default: 0
>  
> +  fsl,broken-auto-tuning:
> +    description: |
> +      Recommend for SDIO cards that enables SDIO interrupt for SDR104 and SDR50 mode.
> +      SDIO interrupt uses DAT[1] to signal the card's interrupt. Auto-tuning circuit
> +      will detect this interrupt on DAT[1] when in 4Bit bus mode, and take it just
> +      as normal data, wrongly adjust the delay cell. This property is used to disable
> +      the auto-tuning function.
> +    type: boolean

Seems like something that could be broken on a variety of hosts and 
should be common?

If auto tuning is broken, shouldn't that speed be disabled?

Rob

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