Re: [PATCH 1/7] ARM: dts: imx: keep the SY7636A VCOM on

[Andreas Kemnade]

On Mon, 26 Oct 2026 00:39:12 +0000
Pablo Mazzini <pmazzini@xxxxxxxxx> wrote:

> The SY7636A hwmon driver turns VCOM on at probe. The reMarkable 2, Kobo
> Libra H2O and Tolino Vision 5 have had the rails on so far. Mark VCOM
> always-on before the driver stops doing it.
> 
> Signed-off-by: Pablo Mazzini <pmazzini@xxxxxxxxx>
> ---
>  arch/arm/boot/dts/nxp/imx/e70k02.dtsi           | 1 +
>  arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/nxp/imx/e70k02.dtsi b/arch/arm/boot/dts/nxp/imx/e70k02.dtsi
> index dc7ff108aa85..bd9c6c6fa117 100644
> --- a/arch/arm/boot/dts/nxp/imx/e70k02.dtsi
> +++ b/arch/arm/boot/dts/nxp/imx/e70k02.dtsi
> @@ -154,6 +154,7 @@ sy7636: pmic@62 {
>  		regulators {
>  			reg_epdpmic: vcom {
>  				regulator-name = "vcom";
> +				regulator-always-on;
>  			};
>  		};
>  	};
No, please not. That regulator is in practice used with a not yet upstreamed
driver for the EPDC on that platform used to deal with the current kernels
fp9931 / tps65185 drivers. So it is very welcome to have it not always turned
on.


> diff --git a/arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts b/arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts
> index ff9d50942884..6cf5603c0752 100644
> --- a/arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts
> +++ b/arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts
> @@ -327,6 +327,7 @@ sy7636a: pmic@62 {
>  		regulators {
>  			reg_epdpmic: vcom {
>  				regulator-name = "vcom";
> +				regulator-always-on;
>  				regulator-boot-on;
>  			};
>  		};


Here the situation is a bit different. If I remember correctly, there
is some special EPD logic in userspace on top of some ordinary kernel
display driver. But thesse things are missing is devicetree?! But
that might need to learn to deal with regulator enabling/disabling.

Regulator always on is probably not desired here, either.

Regards,
Andreas