[PATCH 1/2] ARM: dts: imx8m: increase off-on delay on the SD Vcc regulator

[Peter Robinson]

On Tue, Dec 1, 2020 at 1:31 PM Andrey Zhizhikin
<andrey.zhizhikin at leica-geosystems.com> wrote:
>
> Some SD Card controller and power circuitry has increased capacitance,
> which keeps the internal logic remains powered after regulator is switch
> off. This is generally the case when card is switched to SD104 mode,
> where a power cycle should be performed. In case if the card internal
> logic remains powered, it causes a subsequent failure of mode
> transition, effectively leading to failed enumeration.
>
> Introduce a delay of 20 msec in order to provide a possibility for
> internal card circuitry to drain voltages and perform a power cycle
> correctly.
>
> Similar fix is done in commit c49d0ac38a76 ("ARM: dts: rmobile: Increase
> off-on delay on the SD Vcc regulator") targeted Renesas SOCs.
>
> Signed-off-by: Andrey Zhizhikin <andrey.zhizhikin at leica-geosystems.com>
> Cc: Stefano Babic <sbabic at denx.de>
> ---
>  arch/arm/dts/imx8mm-beacon-kit-u-boot.dtsi | 4 ++++
>  arch/arm/dts/imx8mm-evk-u-boot.dtsi        | 4 ++++
>  arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi   | 4 ++++
>  arch/arm/dts/imx8mp-evk-u-boot.dtsi        | 4 ++++
>  arch/arm/dts/imx8mq-evk.dts                | 1 +
>  arch/arm/dts/imx8mq-phanbell.dts           | 1 +
>  6 files changed, 18 insertions(+)
>
> diff --git a/arch/arm/dts/imx8mm-beacon-kit-u-boot.dtsi b/arch/arm/dts/imx8mm-beacon-kit-u-boot.dtsi
> index fc1aebb2fe..6d80a529ae 100644
> --- a/arch/arm/dts/imx8mm-beacon-kit-u-boot.dtsi
> +++ b/arch/arm/dts/imx8mm-beacon-kit-u-boot.dtsi
> @@ -37,6 +37,10 @@
>         /delete-property/ assigned-clock-rates;
>  };
>
> +&reg_usdhc2_vmmc {
> +       u-boot,off-on-delay-us = <20000>;
> +};
> +
>  &fec1 {
>         phy-reset-gpios = <&gpio4 22 GPIO_ACTIVE_LOW>;
>  };
> diff --git a/arch/arm/dts/imx8mm-evk-u-boot.dtsi b/arch/arm/dts/imx8mm-evk-u-boot.dtsi
> index b5c12105a9..9f77d3c6ff 100644
> --- a/arch/arm/dts/imx8mm-evk-u-boot.dtsi
> +++ b/arch/arm/dts/imx8mm-evk-u-boot.dtsi
> @@ -46,6 +46,10 @@
>         u-boot,dm-spl;
>  };
>
> +&reg_usdhc2_vmmc {
> +       u-boot,off-on-delay-us = <20000>;
> +};
> +
>  &pinctrl_reg_usdhc2_vmmc {
>         u-boot,dm-spl;
>  };
> diff --git a/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi b/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
> index 4419679d4c..98b0b9891b 100644
> --- a/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
> +++ b/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
> @@ -47,6 +47,10 @@
>         u-boot,dm-spl;
>  };
>
> +&reg_usdhc2_vmmc {
> +       u-boot,off-on-delay-us = <20000>;
> +};
> +
>  &pinctrl_uart2 {
>         u-boot,dm-spl;
>  };
> diff --git a/arch/arm/dts/imx8mp-evk-u-boot.dtsi b/arch/arm/dts/imx8mp-evk-u-boot.dtsi
> index 24a93ac2d6..2452e9175c 100644
> --- a/arch/arm/dts/imx8mp-evk-u-boot.dtsi
> +++ b/arch/arm/dts/imx8mp-evk-u-boot.dtsi
> @@ -48,6 +48,10 @@
>         u-boot,dm-spl;
>  };
>
> +&reg_usdhc2_vmmc {
> +       u-boot,off-on-delay-us = <20000>;
> +};
> +
>  &reg_usdhc2_vmmc {
>         u-boot,dm-spl;
>  };
> diff --git a/arch/arm/dts/imx8mq-evk.dts b/arch/arm/dts/imx8mq-evk.dts
> index 55294ba9c8..9663683f69 100644
> --- a/arch/arm/dts/imx8mq-evk.dts
> +++ b/arch/arm/dts/imx8mq-evk.dts
> @@ -39,6 +39,7 @@
>                 regulator-max-microvolt = <3300000>;
>                 gpio = <&gpio2 19 GPIO_ACTIVE_HIGH>;
>                 enable-active-high;
> +               u-boot,off-on-delay-us = <20000>;

These should be going in the -u-boot.dtsi like the devices above. Why
the two different ways of doing it? Also if all devices based on the
imx8m[mnpq
] need this change it might be better putting it in the
imx8m[mnpq]-u-boot.dtsi so any new boards that get added, like the
recently posted imx8mm IoT Gate automatically benefit from this fix.

>         };
>
>         buck2_reg: regulator-buck2 {
> diff --git a/arch/arm/dts/imx8mq-phanbell.dts b/arch/arm/dts/imx8mq-phanbell.dts
> index 4892ad5ee1..bc6b2638ee 100644
> --- a/arch/arm/dts/imx8mq-phanbell.dts
> +++ b/arch/arm/dts/imx8mq-phanbell.dts
> @@ -34,6 +34,7 @@
>                 regulator-max-microvolt = <3300000>;
>                 gpio = <&gpio2 19 GPIO_ACTIVE_HIGH>;
>                 enable-active-high;
> +               u-boot,off-on-delay-us = <20000>;
>         };
>  };
>
> --
> 2.17.1
>