Re: [PATCH v2 4/6] dt-bindings: iio: adc: mcp320x: Update for mcp3550/1/3

[Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On Sat, 9 Sep 2017 20:32:41 +0200
Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> wrote:

> All chips supported by this driver clock data out on the falling edge
> and latch data in on the rising edge, hence SPI mode (0,0) or (1,1)
> must be used.
> 
> Furthermore, none of the chips has an internal reference voltage
> regulator, so an external supply is always required and needs to be
> specified in the device tree lest the IIO "scale" in sysfs cannot be
> calculated.
> 
> Document these requirements in the device tree binding, add compatible
> strings for the newly supported mcp3550/1/3 and explain that SPI mode
> (0,0) should be preferred for these chips.
> 
> Cc: Mathias Duckeck <m.duckeck-XB/JSsFECOqzQB+pC5nmwQ@public.gmane.org>
> Signed-off-by: Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>

I'm happy with this, but just want to give Rob / Mark more time to take
a look at it.

Give me a poke if I seem to have forgotten it in a week or so.

Thanks,

Jonathan
> ---
> Changes since v1:
> - Move support for continuous conversion mode to separate patch
>   which is marked informational / not for merging. (Rob, Jonathan)
> 
>  Documentation/devicetree/bindings/iio/adc/mcp320x.txt | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/mcp320x.txt b/Documentation/devicetree/bindings/iio/adc/mcp320x.txt
> index bcd3ac8e6e0c..7d64753df949 100644
> --- a/Documentation/devicetree/bindings/iio/adc/mcp320x.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/mcp320x.txt
> @@ -29,15 +29,29 @@ Required properties:
>  				"microchip,mcp3204"
>  				"microchip,mcp3208"
>  				"microchip,mcp3301"
> +				"microchip,mcp3550-50"
> +				"microchip,mcp3550-60"
> +				"microchip,mcp3551"
> +				"microchip,mcp3553"
>  
>  			NOTE: The use of the compatibles with no vendor prefix
>  			is deprecated and only listed because old DT use them.
>  
> +	- spi-cpha, spi-cpol (boolean):
> +			Either SPI mode (0,0) or (1,1) must be used, so specify
> +			none or both of spi-cpha, spi-cpol.  The MCP3550/1/3
> +			is more efficient in mode (1,1) as only 3 instead of
> +			4 bytes need to be read from the ADC, but not all SPI
> +			masters support it.
> +
> +	- vref-supply:	Phandle to the external reference voltage supply.
> +
>  Examples:
>  spi_controller {
>  	mcp3x0x@0 {
>  		compatible = "mcp3002";
>  		reg = <0>;
>  		spi-max-frequency = <1000000>;
> +		vref-supply = <&vref_reg>;
>  	};
>  };