[PATCH v2 1/4] iio: hx711: add data-ready-delay-ns property in DT

[PATCH v2 1/4] iio: hx711: add data-ready-delay-ns property in DT

[Andreas Klinger]

add data-ready-delay-ns property for hx711 ADC
this is the delay after rising PD_SCK until DOUT is read and assumed to be
ready

Signed-off-by: Andreas Klinger <ak@it-klinger.de>
---
 Documentation/devicetree/bindings/iio/adc/avia-hx711.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
index b3629405f568..d0c066e3df69 100644
--- a/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
+++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
@@ -8,11 +8,18 @@ Required properties:
 		See Documentation/devicetree/bindings/gpio/gpio.txt
  - avdd-supply:	Definition of the regulator used as analog supply
 
+Optional properties:
+ - data-ready-delay-ns:	additional delay in nanoseconds between rising of
+			PD_SCK until DOUT is ready
+			should be less then maximum PD_SCK high time which
+			is 50000 in the datasheet
+
 Example:
 weight@0 {
 	compatible = "avia,hx711";
 	sck-gpios = <&gpio3 10 GPIO_ACTIVE_HIGH>;
 	dout-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
 	avdd-suppy = <&avdd>;
+	data-ready-delay-ns = <1000>;
 };
 
-- 
2.1.4

Re: [PATCH v2 1/4] iio: hx711: add data-ready-delay-ns property in DT

[Jonathan Cameron]

On Mon, 25 Jun 2018 17:18:02 +0200
Andreas Klinger <ak@it-klinger.de> wrote:

> add data-ready-delay-ns property for hx711 ADC
> this is the delay after rising PD_SCK until DOUT is read and assumed to be
> ready
> 
> Signed-off-by: Andreas Klinger <ak@it-klinger.de>

Hmm. It's not particularly generic... I think this should have
have vendor prefix until we have some visibility of whether it
is a common thing we want to standardise around or not.

I'll also be waiting for a devicetree ack on this one as it's a
tiny bit unusual.

Thanks,

Jonathan
> ---
>  Documentation/devicetree/bindings/iio/adc/avia-hx711.txt | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> index b3629405f568..d0c066e3df69 100644
> --- a/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> @@ -8,11 +8,18 @@ Required properties:
>  		See Documentation/devicetree/bindings/gpio/gpio.txt
>   - avdd-supply:	Definition of the regulator used as analog supply
>  
> +Optional properties:
> + - data-ready-delay-ns:	additional delay in nanoseconds between rising of
> +			PD_SCK until DOUT is ready
> +			should be less then maximum PD_SCK high time which
> +			is 50000 in the datasheet
> +
>  Example:
>  weight@0 {
>  	compatible = "avia,hx711";
>  	sck-gpios = <&gpio3 10 GPIO_ACTIVE_HIGH>;
>  	dout-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
>  	avdd-suppy = <&avdd>;
> +	data-ready-delay-ns = <1000>;
>  };
>  

Re: [PATCH v2 1/4] iio: hx711: add data-ready-delay-ns property in DT

[Rob Herring]

On Sat, Jun 30, 2018 at 06:32:32PM +0100, Jonathan Cameron wrote:
> On Mon, 25 Jun 2018 17:18:02 +0200
> Andreas Klinger <ak@it-klinger.de> wrote:
> 
> > add data-ready-delay-ns property for hx711 ADC
> > this is the delay after rising PD_SCK until DOUT is read and assumed to be
> > ready
> > 
> > Signed-off-by: Andreas Klinger <ak@it-klinger.de>
> 
> Hmm. It's not particularly generic... I think this should have
> have vendor prefix until we have some visibility of whether it
> is a common thing we want to standardise around or not.

Agreed. Doesn't look like any interface I've seen before.

Since it's bit-banging, seems to me it would be better to specify the 
frequency for PD_SCK and sample DOUT just before or after setting PD_SCK 
low. 

Rob

> I'll also be waiting for a devicetree ack on this one as it's a
> tiny bit unusual.
> 
> Thanks,
> 
> Jonathan