Re: [PATCH v3 2/4] dt-bindings: iio: magnetometer: ak8975: add gpio reset support

[Stephan Gerhold <stephan@gerhold.net>]

On Tue, May 19, 2020 at 02:43:52PM +0200, Jonathan Albrieux wrote:
> Add reset-gpio support.
> 
> Without reset's deassertion during ak8975_power_on(), driver's probe fails
> on ak8975_who_i_am() while checking for device identity for AK09911 chip.
> 
> AK09911 has an active low reset gpio to handle register's reset.
> AK09911 datasheed says that, if not used, reset pin should be connected

datasheed -> datasheet

> to VID. This patch emulates this situation.
> 
> Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
> ---
>  .../devicetree/bindings/iio/magnetometer/ak8975.yaml          | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml
> index 86e3efa693a8..a82c0ff5d098 100644
> --- a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml
> +++ b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml
> @@ -37,6 +37,9 @@ properties:
>    mount-matrix:
>      description: an optional 3x3 mounting rotation matrix
>  
> +  reset-gpio:
> +    description: an optional pin needed for AK09911 to set the reset state

Maybe add a comment that this should be "usually active low".

> +
>  required:
>    - compatible
>    - reg
> @@ -53,6 +56,7 @@ examples:
>              reg = <0x0c>;
>              gpios = <&gpj0 7 0>;
>              vdd-supply = <&ldo_3v3_gnss>;
> +            reset-gpio = <&msmgpio 111 1>;

Same here, reset-gpio = <&msmgpio 111 GPIO_ACTIVE_LOW>,
would be more clear.

>              mount-matrix = "-0.984807753012208",  /* x0 */
>                             "0",                   /* y0 */
>                             "-0.173648177666930",  /* z0 */
> -- 
> 2.17.1