[PATCH] arm64: dts: imx8mm-verdin: Link reg_nvcc_sd to usdhc2

[Dubowik Wojciech LCPF-CH]

> From: Francesco Dolcini <francesco at dolcini.it>
> Sent: Thursday, 17 April 2025 15:03
> To: Dubowik Wojciech LCPF-CH <Wojciech.Dubowik at mt.com>
> Cc: linux-kernel at vger.kernel.org <linux-kernel at vger.kernel.org>; Rob Herring <robh at kernel.org>; Krzysztof Kozlowski <krzk+dt at kernel.org>; Conor Dooley <conor+dt at kernel.org>; Shawn Guo <shawnguo at kernel.org>; Sascha Hauer <s.hauer at pengutronix.de>; Pengutronix Kernel Team > <kernel at pengutronix.de>; Fabio Estevam <festevam at gmail.com>; devicetree at vger.kernel.org <devicetree at vger.kernel.org>; imx at lists.linux.dev <imx at lists.linux.dev>; linux-arm-kernel at lists.infradead.org <linux-arm-kernel at lists.infradead.org>; stable at vger.kernel.org <stable at vger.kernel.org>
> Subject: Re: EXTERNAL - [PATCH] arm64: dts: imx8mm-verdin: Link reg_nvcc_sd to usdhc2
 
> Hello Wojciech,
> thanks very much for your patch.

> On Thu, Apr 17, 2025 at 01:20:11PM +0200, Wojciech Dubowik wrote:
>> Link LDO5 labeled reg_nvcc_sd from PMIC to align with
>> hardware configuration specified in the datasheet.
>>
>> Without this definition LDO5 will be powered down, disabling
>> SD card after bootup. This has been introduced in commit
>> f5aab0438ef1 (regulator: pca9450: Fix enable register for LDO5).
>>
>> Fixes: f5aab0438ef1 (regulator: pca9450: Fix enable register for LDO5)
>> Cc: stable at vger.kernel.org
>>
>> Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik at mt.com>
>> ---
>>  arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi b/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
>> index 7251ad3a0017..6307c5caf3bc 100644
>> --- a/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
>> +++ b/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi
>> @@ -785,6 +785,7 @@ &usdhc2 {
>>        pinctrl-2 = <&pinctrl_usdhc2_200mhz>, <&pinctrl_usdhc2_cd>;
>>        pinctrl-3 = <&pinctrl_usdhc2_sleep>, <&pinctrl_usdhc2_cd_sleep>;
>>        vmmc-supply = <&reg_usdhc2_vmmc>;
>> +     vqmmc-supply = <&reg_nvcc_sd>;
>
>I am worried just doing this will have some side effects.
>
>Before this patch, the switch between 1v8 and 3v3 was done because we
>have a GPIO, connected to the PMIC, controlled by the USDHC2 instance
>(MX8MM_IOMUXC_GPIO1_IO04_USDHC2_VSELECT, see pinctrl_usdhc2).
>
>With your change both the PMIC will be programmed with a different
>voltage over i2c and the GPIO will also toggle. It does not sound like
>what we want to do.
>
>Maybe we should have a "regulator-gpio" with vin-supply =
><&reg_nvcc_sd>, as we recently did here
>https://lore.kernel.org/all/20250414123827.428339-1-ivitro@gmail.com/T/#m2964f1126a6732a66a6e704812f2b786e8237354
>?

>Francesco
I will have a look at your suggestion and try to test them on verdin. I won't have access to HW over Eastern so the patch will have to wait.

Wojtek