[U-Boot] [PATCH 1/1] Set VLD04 output to 2.8V in PMIC initialization.

[mind entropy]

On Tue, Jun 27, 2017 at 10:54 PM, Fabio Estevam <festevam at gmail.com> wrote:

> Hi Gautam,
>
> On Wed, Jun 21, 2017 at 1:18 PM, Gautam Bhat <mindentropy at gmail.com>
> wrote:
> > This change sets the VLDO4 settings output to 2.8V in PMIC
> > initialization so that the MIPI DSI and MIPI CSI input voltage
> > is 2.8V as per the schematics.
>
> As we do not have MIPI DSI / MIPI CSI support in U-Boot, it is
> preferable to let the kernel configure the regulator.
>
> You can do this is the device tree like this:
>
> diff --git a/arch/arm/boot/dts/imx7d-sdb.dts
> b/arch/arm/boot/dts/imx7d-sdb.dts
> index 54c4540..923aa755 100644
> --- a/arch/arm/boot/dts/imx7d-sdb.dts
> +++ b/arch/arm/boot/dts/imx7d-sdb.dts
> @@ -285,8 +285,8 @@
>                         };
>
>                         vgen6_reg: vldo4 {
> -                               regulator-min-microvolt = <1800000>;
> -                               regulator-max-microvolt = <3300000>;
> +                               regulator-min-microvolt = <2800000>;
> +                               regulator-max-microvolt = <2800000>;
>                                 regulator-always-on;
>                         };
>                 };
>
> Regards,
>
> Fabio Estevam
>

​Hi Fabio,

The patch for the kernel was supposed to be next. Should I send the kernel
patch to mainline or some place else?

Coming to u-boot, the fact that even if there is no MIPI DSI/MIPI CSI
support the voltage would still be 3.3V in those rails. In my case I do not
attach the display after u-boot boots up. I keep the display attached and
sometimes I leave it in u-boot command line without going over to the
kernel. Since this is a development board this is often the case for many
developers and there may be chances of the display getting damaged.

Thanks,
Gautam.

​