linux-kernel - Re: [PATCH v5 6/6] drivers:iio:dac:ad5766.c: Add trigger buffer

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Message-ID: <CA+U=DsrNExNT2Bvjve80GJwBPy3pH_gmhc5vjYTbnsh65MHNHQ@mail.gmail.com>
Date:   Fri, 17 Sep 2021 11:08:24 +0300
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Mihail Chindris <mihail.chindris@...log.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        "Hennerich, Michael" <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Nuno Sá <nuno.sa@...log.com>,
        "Bogdan, Dragos" <dragos.bogdan@...log.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Subject: Re: [PATCH v5 6/6] drivers:iio:dac:ad5766.c: Add trigger buffer

On Fri, Sep 17, 2021 at 9:11 AM Mihail Chindris
<mihail.chindris@...log.com> wrote:
>
> This chip is able to generate waveform and using an
> with the output trigger buffer will be easy to generate one.
>

This turned out to look quite neat.
Some minor notes inline.
Nothing major.
But other than that:

Reviewed-by: Alexandru Ardelean <ardeleanalex@...il.com>

> Signed-off-by: Mihail Chindris <mihail.chindris@...log.com>
> ---
>  drivers/iio/dac/ad5766.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
>
> diff --git a/drivers/iio/dac/ad5766.c b/drivers/iio/dac/ad5766.c
> index dafda84fdea3..71491e6d466e 100644
> --- a/drivers/iio/dac/ad5766.c
> +++ b/drivers/iio/dac/ad5766.c
> @@ -5,10 +5,13 @@
>   * Copyright 2019-2020 Analog Devices Inc.
>   */
>  #include <linux/bitfield.h>
> +#include <linux/bitops.h>
>  #include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/iio/iio.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>
>  #include <linux/module.h>
>  #include <linux/spi/spi.h>
>  #include <asm/unaligned.h>
> @@ -41,6 +44,7 @@
>  #define AD5766_CMD_DITHER_SCALE_2              0xD0
>
>  #define AD5766_FULL_RESET_CODE                 0x1234
> +#define AD5766_NUM_CH                          16
>
>  enum ad5766_type {
>         ID_AD5766,
> @@ -455,6 +459,7 @@ static const struct iio_chan_spec_ext_info ad5766_ext_info[] = {
>         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),                   \
>         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |         \
>                 BIT(IIO_CHAN_INFO_SCALE),                               \
> +       .scan_index = (_chan),                                          \
>         .scan_type = {                                                  \
>                 .sign = 'u',                                            \
>                 .realbits = (_bits),                                    \
> @@ -576,6 +581,28 @@ static int ad5766_default_setup(struct ad5766_state *st)
>         return  __ad5766_spi_write(st, AD5766_CMD_SPAN_REG, st->crt_range);
>  }
>
> +static irqreturn_t ad5766_trigger_handler(int irq, void *p)
> +{
> +       struct iio_poll_func *pf = p;
> +       struct iio_dev *indio_dev = pf->indio_dev;
> +       struct iio_buffer *buf = indio_dev->buffer;

Purely stylistic.
I would keep the variable name as "struct iio_buffer *bufffer".
Reason is: when you start to grep the kernel-code, `buf` tends to
refer to simple/small buffers (like buf[4], or buf[16]).
And when wanting to do some multiple-changes, grepping easier is useful.

> +       int ret, ch, i;
> +       u16 data[AD5766_NUM_CH];
> +
> +       ret = iio_pop_from_buffer(buf, (u8 *)data);

Does the compiler complain if this (u8 *) cast is removed?
Because it doesn't look like this is needed or that it would do
anything as the argument of data is (void *).

> +       if (ret)
> +               goto done;
> +
> +       i = 0;
> +       for_each_set_bit(ch, indio_dev->active_scan_mask, AD5766_NUM_CH - 1)
> +               ad5766_write(indio_dev, ch, le16_to_cpu(data[i++]));
> +
> +done:
> +       iio_trigger_notify_done(indio_dev->trig);
> +
> +       return IRQ_HANDLED;
> +}
> +
>  static int ad5766_probe(struct spi_device *spi)
>  {
>         enum ad5766_type type;
> @@ -609,6 +636,15 @@ static int ad5766_probe(struct spi_device *spi)
>         if (ret)
>                 return ret;
>
> +       /* Configure trigger buffer */
> +       ret = devm_iio_triggered_buffer_setup_ext(&spi->dev, indio_dev, NULL,
> +                                                 ad5766_trigger_handler,
> +                                                 IIO_BUFFER_DIRECTION_OUT,
> +                                                 NULL,
> +                                                 NULL);
> +       if (ret)
> +               return ret;
> +
>         return devm_iio_device_register(&spi->dev, indio_dev);
>  }
>
> --
> 2.27.0
>