Re: [PATCH 2/3] Documentation: dt: iio: add mcp4725/6 dac device binding

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

On 01/10/16 12:15, Jonathan Cameron wrote:
> On 30/09/16 14:19, Tomas Novotny wrote:
>> Signed-off-by: Tomas Novotny <tomas-P46umIhNmdHrBKCeMvbIDA@public.gmane.org>
>> ---
>>  .../devicetree/bindings/iio/dac/mcp4725.txt        | 28 ++++++++++++++++++++++
>>  1 file changed, 28 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/iio/dac/mcp4725.txt
>>
>> diff --git a/Documentation/devicetree/bindings/iio/dac/mcp4725.txt b/Documentation/devicetree/bindings/iio/dac/mcp4725.txt
>> new file mode 100644
>> index 0000000..69c9462
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/dac/mcp4725.txt
>> @@ -0,0 +1,28 @@
>> +Microchpip mcp4725 and mcp4726 DAC device driver
>> +
>> +Required properties:
>> +	- compatible: Must be "microchip,mcp4725" or "microchip,mcp4726"
>> +	- reg: Should contain the DAC I2C address
>> +	- vref-millivolt: Value of the reference voltage
Sorry dozing this morning so missed this until looking at the code.

Use the regulator framework to supply two regulators:

vref-suppy and vdd-supply
first one optional.

Then query them in the driver.  Much more flexible than just hard coding
a value here.  Entirely possible to have a variable regulator used for
the reference.
>> +
>> +Optional properties:
>> +	- vref-mode: Reference voltage selection. It is available only on
> Not a generic attribute, so wants to have a vendor prefix on it.
>> +	  mcp4726. Valid values are:
>> +		- 0, 1: Vdd pin voltage (unbuffered)
> This should not be a direct mapping of the register values but rather
> a means to control the setting.  Having two values mapping to the
> same thing makes no sense.
> 
> Would also be odd to specify a vref and then not use it.  So you could
> infer this first option.
>> +		- 2: Vref pin voltage unbuffered
>> +		- 3: Vref pin voltage internally buffered
> Having inferred the first option then this becomes control of whether it
> is buffered  or not. So could be named appropriately to cover that.
> Might be nice to have a little note here on why you might want the
> buffer or not..
>> +
>> +Examples:
>> +
>> +        mcp4725@60 {
>> +                compatible = "microchip,mcp4725";
>> +                reg = <0x60>;
>> +                vref-millivolt = <3300>;
>> +        };
>> +
>> +        mcp4726@60 {
>> +                compatible = "microchip,mcp4726";
>> +                reg = <0x60>;
>> +                vref-mode = <2>;
>> +                vref-millivolt = <2500>;

>> +        };
>>
> 
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