Re: [PATCH 3/4] [media] ad5820: DT new optional field enable-gpios

Laurent Pinchart
2018-09-21T02:06:31Z

Hi Ricardo,

Thank you for the patch.

On Thursday, 20 September 2018 19:19:11 EEST Ricardo Ribalda Delgado wrote:
> Document new enable-gpio field. It can be used to disable the part
> without turning down its regulator.
>
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> ---
> Documentation/devicetree/bindings/media/i2c/ad5820.txt | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/media/i2c/ad5820.txt
> b/Documentation/devicetree/bindings/media/i2c/ad5820.txt index
> 5940ca11c021..07d577bb37f7 100644
> --- a/Documentation/devicetree/bindings/media/i2c/ad5820.txt
> +++ b/Documentation/devicetree/bindings/media/i2c/ad5820.txt
> @@ -8,6 +8,11 @@ Required Properties:
>
> - VANA-supply: supply of voltage for VANA pin
>
> +Optional properties:
> +
> + - enable-gpios : GPIO spec for the XSHUTDOWN pin.

xshutdown is active-low, so enable is active-high. Should this be documented
explicitly, to avoid polarity errors ? Maybe something along the lines of

- enable-gpios: GPIO spec for the XSHUTDOWN pin. Note that the polarity of the
enable GPIO is the opposite of the XSHUTDOWN pin (asserting the enable GPIO
deasserts the XSHUTDOWN signal and vice versa).

> If specified, it will be
> + asserted when VANA-supply is enabled.

That documents a driver behaviour, is it needed in DT ?

> Example:
>
> ad5820: coil@c {
> @@ -15,5 +20,6 @@ Example:
> reg = <0x0c>;
>
> VANA-supply = <&vaux4>;
> + enable-gpios = <&msmgpio 26 GPIO_ACTIVE_HIGH>;
> };

--
Regards,

Laurent Pinchart