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

Stephan Gerhold
2020-05-19T13:26:02Z

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