Re: [PATCH RESEND v3 1/3] dt-bindings: mmc: sdhci-am654: Add ti,suppress-v1p8-ena

Krzysztof Kozlowski
2025-04-25T07:48:22Z

On Tue, Apr 22, 2025 at 05:05:10PM GMT, Judith Mendez wrote:
> Some Microcenter/Patriot SD cards and Kingston eMMC are failing init
> across Sitara K3 boards. Init failure is due to the sequence when
> V1P8_SIGNAL_ENA is set. The V1P8_SIGNAL_ENA has a timing component tied
> to it where if set, switch to full-cycle timing happens. The failing
> cards do not like change to full-cycle timing before changing bus
> width, so add flag to sdhci-am654 binding to suppress V1P8_SIGNAL_ENA
> before changing bus width. The switch to full-cycle timing should happen
> with HIGH_SPEED_ENA after change of bus width.
>
> Signed-off-by: Judith Mendez <jm@ti.com>
> ---
> Documentation/devicetree/bindings/mmc/sdhci-am654.yaml | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml b/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
> index 676a74695389..0f92bbf8e13b 100644
> --- a/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
> @@ -201,6 +201,11 @@ properties:
> and the controller is required to be forced into Test mode
> to set the TESTCD bit.
>
> + ti,suppress-v1p8-ena:

Do not tell what the drivers should do, but tell what is the issue with
the hardware, e.g. some cards do not like full-cycle.... and this will
also hint you that it should be most likely generic, not specific to
this device.

> + $ref: /schemas/types.yaml#/definitions/flag
> + description:

Best regards,
Krzysztof