linux-kernel - Re: [PATCH v7 1/8] iio: adc: ad7606: add 'bits' parameter to channels macros

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Message-ID: <CA+GgBR94rNX4wLh527EmfO4pzYFU02fQOr-KfzMt6Reyb5QFgA@mail.gmail.com>
Date: Tue, 24 Sep 2024 10:11:38 +0200
From: Alexandru Ardelean <aardelean@...libre.com>
To: David Lechner <dlechner@...libre.com>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org, jic23@...nel.org, krzk+dt@...nel.org, 
	robh@...nel.org, lars@...afoo.de, michael.hennerich@...log.com, 
	gstols@...libre.com
Subject: Re: [PATCH v7 1/8] iio: adc: ad7606: add 'bits' parameter to channels macros

On Mon, Sep 23, 2024 at 4:51 PM David Lechner <dlechner@...libre.com> wrote:
>
> On Thu, Sep 19, 2024 at 3:04 PM Alexandru Ardelean
> <aardelean@...libre.com> wrote:
> >
> > There are some newer additions to the AD7606 family, which support 18 bit
> > precision. Up until now, all chips were 16 bit.
> >
> > This change adds a 'bits' parameter to the AD760X_CHANNEL macro and renames
> > 'ad7606_channels' -> 'ad7606_channels_16bit' for the current devices.
> >
> > The AD7606_SW_CHANNEL() macro is also introduced, as a short-hand for IIO
> > channels in SW mode.
> >
> > Signed-off-by: Alexandru Ardelean <aardelean@...libre.com>
> > ---
>
> ...
>
> > diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
> > index 6649e84d25de..204a343067e5 100644
> > --- a/drivers/iio/adc/ad7606.h
> > +++ b/drivers/iio/adc/ad7606.h
> > @@ -8,7 +8,7 @@
> >  #ifndef IIO_ADC_AD7606_H_
> >  #define IIO_ADC_AD7606_H_
> >
> > -#define AD760X_CHANNEL(num, mask_sep, mask_type, mask_all) {   \
> > +#define AD760X_CHANNEL(num, mask_sep, mask_type, mask_all, bits) {     \
> >                 .type = IIO_VOLTAGE,                            \
> >                 .indexed = 1,                                   \
> >                 .channel = num,                                 \
> > @@ -19,24 +19,26 @@
> >                 .scan_index = num,                              \
> >                 .scan_type = {                                  \
> >                         .sign = 's',                            \
> > -                       .realbits = 16,                         \
> > -                       .storagebits = 16,                      \
> > +                       .realbits = (bits),                     \
> > +                       .storagebits = (bits) > 16 ? 32 : 16,   \
> >                         .endianness = IIO_CPU,                  \
> >                 },                                              \
> >  }
> >
> >  #define AD7605_CHANNEL(num)                            \
> >         AD760X_CHANNEL(num, BIT(IIO_CHAN_INFO_RAW),     \
> > -               BIT(IIO_CHAN_INFO_SCALE), 0)
> > +               BIT(IIO_CHAN_INFO_SCALE), 0, 16)
> >
> > -#define AD7606_CHANNEL(num)                            \
> > +#define AD7606_CHANNEL(num, bits)                      \
> >         AD760X_CHANNEL(num, BIT(IIO_CHAN_INFO_RAW),     \
> >                 BIT(IIO_CHAN_INFO_SCALE),               \
> > -               BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO))
> > +               BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), bits)
> >
> > -#define AD7616_CHANNEL(num)    \
> > +#define AD7606_SW_CHANNEL(num, bits)   \
> >         AD760X_CHANNEL(num, BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),\
> > -               0, BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO))
> > +               0, BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), bits)
> > +
> > +#define AD7616_CHANNEL(num)    AD7606_SW_CHANNEL(num, 16)
>
> It looks like the AD7616_CHANNEL macro is no longer used, so can be
> dropped. Or alternately, don't change the lines below to use
> AD7606_SW_CHANNEL.

Well, the AD7616_CHANNEL() macro is still being used for the actual
AD7616 channels.
For the AD7606B software channels, the AD7616_CHANNEL() macro was
being re-used, which seemed like a bit of a lazy/convenient way to do
it.

The patch here, just cleans up that minor quirk, but just for AD7606B.
The AD7616 driver part, still uses the AD7616_CHANNEL() macro.

Though, interestingly, the AD7616_CHANNEL() macro is only used for SW channels.
Maybe in a subsequent patch, the AD7616_CHANNEL() macro can be removed
altogether.
I thought about doing it in this series, but decided against it, to
keep the series small.

>
> With either of those changes:
>
> Reviewed-by: David Lechner <dlechner@...libre.com>
>
> >
> >  /**
> >   * struct ad7606_chip_info - chip specific information
> > diff --git a/drivers/iio/adc/ad7606_spi.c b/drivers/iio/adc/ad7606_spi.c
> > index 62ec12195307..e00f58a6a0e9 100644
> > --- a/drivers/iio/adc/ad7606_spi.c
> > +++ b/drivers/iio/adc/ad7606_spi.c
> > @@ -67,14 +67,14 @@ static const struct iio_chan_spec ad7616_sw_channels[] = {
> >
> >  static const struct iio_chan_spec ad7606b_sw_channels[] = {
> >         IIO_CHAN_SOFT_TIMESTAMP(8),
> > -       AD7616_CHANNEL(0),
> > -       AD7616_CHANNEL(1),
> > -       AD7616_CHANNEL(2),
> > -       AD7616_CHANNEL(3),
> > -       AD7616_CHANNEL(4),
> > -       AD7616_CHANNEL(5),
> > -       AD7616_CHANNEL(6),
> > -       AD7616_CHANNEL(7),
> > +       AD7606_SW_CHANNEL(0, 16),
> > +       AD7606_SW_CHANNEL(1, 16),
> > +       AD7606_SW_CHANNEL(2, 16),
> > +       AD7606_SW_CHANNEL(3, 16),
> > +       AD7606_SW_CHANNEL(4, 16),
> > +       AD7606_SW_CHANNEL(5, 16),
> > +       AD7606_SW_CHANNEL(6, 16),
> > +       AD7606_SW_CHANNEL(7, 16),
> >  };
> >
> >  static const unsigned int ad7606B_oversampling_avail[9] = {
> > --
> > 2.46.0
> >