On Tue, Nov 15, 2016 at 1:52 PM, Clemens Gruber
<clemens.gruber@xxxxxxxxxxxx> wrote:
> Hi,
>
> I am preparing a patch for the ina2xx driver to allow configuring the
> PGA bits (which define the shunt voltage range) and the BRNG bit (which
> defines the bus voltage range) from the device tree.
> We have multiple INA219 with different voltage ranges, so I can't just
> change the hardcoded default in ina2xx.c
> The ADC averaging setting should also be configurable.
>
> Now I am asking myself if I should create several new DT properties or
> rather add one config-reg property to set a different default value for
> the 16-bit configuration register (instead of the driver defaults of
> 0x399F for the INA219 and 0x4527 for the INA226) ?
>
> Solution A:
Generally, this is preferred.
> ina219_foo: ina219@44 {
> compatible = "ti,ina219";
> reg = <0x44>;
> shunt-resistor = <25000>;
>
> pga = <2>; /* PGA Gain /2 instead of the default /8 */
> /* Note: Possible PGA Gain values are /1, /2, /4 and /8 */
>
> has-16v-brng; /* Bus voltage range of 16V instead of 32V */
>
> averaging = <128>; /* Average 128 samples */
> };
>
> Should each of those also have a sysfs attribute?
These should probably be in DT or in sysfs, but not both. The decision
should be based on how are the settings picked: by the h/w design or
an end user will want to modify them.
> Solution B:
>
> ina219_bar: ina219@45 {
> compatible = "ti,ina219";
> reg = <0x45>;
> shunt-resistor = <25000>;
>
> config-reg = <0x019F>; /* PGA /1, BRNG = 16V, No averaging */
> };
>
> Regards,
> Clemens
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