Re: [PATCH v5 07/10] iio: adc: Support ROHM BD79124 ADC

[Matti Vaittinen]

On 08/03/2025 18:44, Jonathan Cameron wrote:
> On Mon, 3 Mar 2025 13:33:39 +0200
> Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote:
>
> > The ROHM BD79124 is a 12-bit, 8-channel, SAR ADC. The ADC supports
> > an automatic measurement mode, with an alarm interrupt for out-of-window
> > measurements. The window is configurable for each channel.
> >
> > The I2C protocol for manual start of the measurement and data reading is
> > somewhat peculiar. It requires the master to do clock stretching after
> > sending the I2C slave-address until the slave has captured the data.
> > Needless to say this is not well suopported by the I2C controllers.
> >
> > Thus the driver does not support the BD79124's manual measurement mode
> > but implements the measurements using automatic measurement mode relying
> > on the BD79124's ability of storing latest measurements into register.
> >
> > The driver does also support configuring the threshold events for
> > detecting the out-of-window events.
> >
> > The BD79124 keeps asserting IRQ for as long as the measured voltage is
> > out of the configured window. Thus the driver masks the received event
> > for a fixed duration (1 second) when an event is handled. This prevents
> > the user-space from choking on the events
> >
> > The ADC input pins can be also configured as general purpose outputs.
> > Those pins which don't have corresponding ADC channel node in the
> > device-tree will be controllable as GPO.
> >
> > Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
> Hi Matti
>
> Just a few really trivial comments.  If all else in the
> set was resolved I'd probably have applied with a tweak or two
>
> Thanks,
>
> Jonathan
>
> >   obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o
> > diff --git a/drivers/iio/adc/rohm-bd79124.c b/drivers/iio/adc/rohm-bd79124.c
> > new file mode 100644
> > index 000000000000..466c7decf8fc
> > --- /dev/null
> > +++ b/drivers/iio/adc/rohm-bd79124.c
> > @@ -0,0 +1,1108 @@
> ...
>
> > +
> > +/* Read-only regs */
>
> Given naming this is pretty obvious.
> I would drop the comment

I will drop this, although I am not sure it is as self explatonary as 
one thinks. I've seen people getting this wrong because the logic of 
regmap-ranges is kind of reversed. (Eg, read-only is done by adding 
range to wr_tables and not to rd_tables - as a no-range).

Thanks for the review, and rest of the comments just agreed with.

-- Matti