[PATCH v2 1/2] iio: adc: hx711: Add DT binding for avia,hx711

[PATCH v2 1/2] iio: adc: hx711: Add DT binding for avia,hx711

[Andreas Klinger]

Add DT bindings for avia,hx711
Add vendor avia to vendor list

Signed-off-by: Andreas Klinger <ak@it-klinger.de>
---
 .../devicetree/bindings/iio/adc/avia-hx711.txt      | 21 +++++++++++++++++++++
 .../devicetree/bindings/vendor-prefixes.txt         |  1 +
 2 files changed, 22 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/avia-hx711.txt

diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
new file mode 100644
index 000000000000..6a4659fc7a4f
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
@@ -0,0 +1,21 @@
+* AVIA HX711 ADC chip for weight cells
+  Bit-banging driver
+
+Required properties:
+ - compatible: Should be "avia,hx711"
+ - sck-gpios:	Definition of the GPIO for the clock
+ - dout-gpios:	Definition of the GPIO for data-out
+		See Documentation/devicetree/bindings/gpio/gpio.txt
+
+Recommended properties:
+ - gain:	Gain select, can be 32, 64 or 128
+		default is 128
+
+Example:
+weight@0 {
+	compatible = "avia,hx711";
+	sck-gpios = <&gpio3 10 GPIO_ACTIVE_HIGH>;
+	dout-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
+	gain = <32>
+};
+
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index 44ddc980b085..4696bb5c2198 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -32,6 +32,7 @@ atlas	Atlas Scientific LLC
 atmel	Atmel Corporation
 auo	AU Optronics Corporation
 avago	Avago Technologies
+avia	avia semiconductor
 avic	Shanghai AVIC Optoelectronics Co., Ltd.
 axis	Axis Communications AB
 boe	BOE Technology Group Co., Ltd.
-- 
2.1.4

Re: [PATCH v2 1/2] iio: adc: hx711: Add DT binding for avia,hx711

[Lars-Peter Clausen]

On 12/14/2016 10:59 AM, Andreas Klinger wrote:
> Add DT bindings for avia,hx711
> Add vendor avia to vendor list
> 
> Signed-off-by: Andreas Klinger <ak@it-klinger.de>
> ---
>  .../devicetree/bindings/iio/adc/avia-hx711.txt      | 21 +++++++++++++++++++++
>  .../devicetree/bindings/vendor-prefixes.txt         |  1 +
>  2 files changed, 22 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> new file mode 100644
> index 000000000000..6a4659fc7a4f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> @@ -0,0 +1,21 @@
> +* AVIA HX711 ADC chip for weight cells
> +  Bit-banging driver
> +
> +Required properties:
> + - compatible: Should be "avia,hx711"
> + - sck-gpios:	Definition of the GPIO for the clock
> + - dout-gpios:	Definition of the GPIO for data-out
> +		See Documentation/devicetree/bindings/gpio/gpio.txt
> +
> +Recommended properties:
> + - gain:	Gain select, can be 32, 64 or 128
> +		default is 128

If the gain is software programmable it should be exposed by the driver
allowing the application to change it rather than putting it in the devicetree.

Re: [PATCH v2 1/2] iio: adc: hx711: Add DT binding for avia,hx711

[Andreas Klinger]

Hi Lars-Peter,

Lars-Peter Clausen <lars@metafoo.de> schrieb am Wed, 14. Dec 11:11:
> On 12/14/2016 10:59 AM, Andreas Klinger wrote:
> > Add DT bindings for avia,hx711
> > Add vendor avia to vendor list
> > 
> > Signed-off-by: Andreas Klinger <ak@it-klinger.de>
> > ---
> >  .../devicetree/bindings/iio/adc/avia-hx711.txt      | 21 +++++++++++++++++++++
> >  .../devicetree/bindings/vendor-prefixes.txt         |  1 +
> >  2 files changed, 22 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> > new file mode 100644
> > index 000000000000..6a4659fc7a4f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
> > @@ -0,0 +1,21 @@
> > +* AVIA HX711 ADC chip for weight cells
> > +  Bit-banging driver
> > +
> > +Required properties:
> > + - compatible: Should be "avia,hx711"
> > + - sck-gpios:	Definition of the GPIO for the clock
> > + - dout-gpios:	Definition of the GPIO for data-out
> > +		See Documentation/devicetree/bindings/gpio/gpio.txt
> > +
> > +Recommended properties:
> > + - gain:	Gain select, can be 32, 64 or 128
> > +		default is 128
> 
> If the gain is software programmable it should be exposed by the driver
> allowing the application to change it rather than putting it in the devicetree.
> 
There is also a hardware dependency in terms of where to connect the input
channel to:
- gain 64 and gain 128 are available only on input channel A
- gain 32 is only available on input channel B

Do you still think, it should be removed from the devicetree?

Andreas
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Re: [PATCH v2 1/2] iio: adc: hx711: Add DT binding for avia,hx711

[Lars-Peter Clausen]

On 12/14/2016 11:34 AM, Andreas Klinger wrote:
> Hi Lars-Peter,
> 
> Lars-Peter Clausen <lars@metafoo.de> schrieb am Wed, 14. Dec 11:11:
>> On 12/14/2016 10:59 AM, Andreas Klinger wrote:
>>> Add DT bindings for avia,hx711
>>> Add vendor avia to vendor list
>>>
>>> Signed-off-by: Andreas Klinger <ak@it-klinger.de>
>>> ---
>>>  .../devicetree/bindings/iio/adc/avia-hx711.txt      | 21 +++++++++++++++++++++
>>>  .../devicetree/bindings/vendor-prefixes.txt         |  1 +
>>>  2 files changed, 22 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
>>> new file mode 100644
>>> index 000000000000..6a4659fc7a4f
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.txt
>>> @@ -0,0 +1,21 @@
>>> +* AVIA HX711 ADC chip for weight cells
>>> +  Bit-banging driver
>>> +
>>> +Required properties:
>>> + - compatible: Should be "avia,hx711"
>>> + - sck-gpios:	Definition of the GPIO for the clock
>>> + - dout-gpios:	Definition of the GPIO for data-out
>>> +		See Documentation/devicetree/bindings/gpio/gpio.txt
>>> +
>>> +Recommended properties:
>>> + - gain:	Gain select, can be 32, 64 or 128
>>> +		default is 128
>>
>> If the gain is software programmable it should be exposed by the driver
>> allowing the application to change it rather than putting it in the devicetree.
>>
> There is also a hardware dependency in terms of where to connect the input
> channel to:
> - gain 64 and gain 128 are available only on input channel A
> - gain 32 is only available on input channel B
> 
> Do you still think, it should be removed from the devicetree?

I believe so, especially considering that there are two channels and your
driver currently only exposes one of them, which is elected by the gain
configuration. I'd expect that there are use-cases where both inputs are
connected and the application wants to switch between them dynamically at
runtime.

The only tricky part here seems to be that the configuration for the next
conversion is selected on the current conversion. This means you probably
need to do a dummy conversion whenever the settings change.