On Mon, Nov 16, 2020 at 02:52:59PM +0100, Jacopo Mondi wrote:
> Document the 'initial-reverse-channel-mV' vendor property in the
> bindings document of the max9286 driver.
>
> The newly introduced property allows to specifying the initial
> configuration of the GMSL reverse control channel to accommodate
> remote serializers pre-programmed with the high threshold power
> supply noise immunity enabled.
>
> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
> .../bindings/media/i2c/maxim,max9286.yaml | 23 +++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> index 9ea827092fdd..f61234d204fa 100644
> --- a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> @@ -51,6 +51,26 @@ properties:
> '#gpio-cells':
> const: 2
>
> + maxim,initial-reverse-channel-mV:
Use standard unit suffix.
> + $ref: '/schemas/types.yaml#/definitions/uint32'
> + minimum: 30
> + maximum: 200
> + default: 170
> + description: |
> + Initial amplitude of the reverse control channel, in millivolts.
> +
> + The initial amplitude shall be adjusted to a value compatible with the
> + configuration of the connected remote serializer.
> +
> + Some camera modules (for example RDACM20) include an on-board MCU that
> + pre-programs the embedded serializer with power supply noise immunity
> + (high-threshold) enabled. A typical value of the deserializer's reverse
> + channel amplitude to communicate with pre-programmed serializers is 170mV.
> +
> + A typical value for the reverse channel amplitude to communicate with
> + a remote serializer whose high-threshold noise immunity is not enabled
> + is 100mV.
> +
> ports:
> type: object
> description: |
> @@ -221,6 +241,7 @@ required:
> - ports
> - i2c-mux
> - gpio-controller
> + - maxim,initial-reverse-channel-mV
>
> additionalProperties: false
>
> @@ -243,6 +264,8 @@ examples:
> gpio-controller;
> #gpio-cells = <2>;
>
> + maxim,initial-reverse-channel-mV = <170>;
> +
> ports {
> #address-cells = <1>;
> #size-cells = <0>;
> --
> 2.29.1
>
