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Date:   Wed, 26 Aug 2020 19:10:03 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Nishant Malpani <nish.malpani25@...il.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        "Bogdan, Dragos" <dragos.bogdan@...log.com>,
        darius.berghe@...log.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/3] iio: gyro: adxrs290: Add triggered buffer support

On Tue, Aug 25, 2020 at 4:11 PM Nishant Malpani
<nish.malpani25@...il.com> wrote:
>
> Provide a way for continuous data capture by setting up buffer support. The
> data ready signal exposed at the SYNC pin of the ADXRS290 is exploited as
> a hardware interrupt which triggers to fill the buffer.
>
> Triggered buffer setup was tested with both hardware trigger (DATA_RDY) and
> software triggers (sysfs-trig & hrtimer).

...

> +static int adxrs290_set_mode(struct iio_dev *indio_dev, enum adxrs290_mode mode)
> +{
> +       struct adxrs290_state *st = iio_priv(indio_dev);
> +       int val, ret;
> +
> +       mutex_lock(&st->lock);
> +
> +       if (st->mode == mode) {

> +               ret = 0;

Can be done outside of mutex.

> +               goto done;
> +       }
> +

> +       val = spi_w8r8(st->spi, ADXRS290_READ_REG(ADXRS290_REG_POWER_CTL));
> +       if (val < 0) {
> +               ret = val;
> +               goto done;
> +       }

Consider other way around
 ret = ...
 ...
 val = ret;

> +       switch (mode) {
> +       case ADXRS290_MODE_STANDBY:
> +               val &= ~ADXRS290_MEASUREMENT;
> +               break;
> +       case ADXRS290_MODE_MEASUREMENT:
> +               val |= ADXRS290_MEASUREMENT;
> +               break;
> +       default:
> +               ret = -EINVAL;
> +               goto done;
> +       }
> +
> +       ret = adxrs290_spi_write_reg(st->spi,
> +                                    ADXRS290_REG_POWER_CTL,
> +                                    val);
> +       if (ret < 0) {
> +               dev_err(&st->spi->dev, "unable to set mode: %d\n", ret);
> +               goto done;
> +       }
> +
> +       /* update cached mode */
> +       st->mode = mode;
> +
> +done:
> +       mutex_unlock(&st->lock);
> +       return ret;
> +}

...

> +                               goto err_release;
>
> -                       return IIO_VAL_INT;
> +                       ret = IIO_VAL_INT;
> +                       break;
>                 default:
> -                       return -EINVAL;
> +                       ret = -EINVAL;
> +                       break;
>                 }

> +err_release:

I didn't get the purpose of this. Wasn't the break statement enough?

> +               iio_device_release_direct_mode(indio_dev);
> +               return ret;
>         case IIO_CHAN_INFO_SCALE:
>                 switch (chan->type) {
>                 case IIO_ANGL_VEL:

...

> +                       goto err_release;

Ditto.

> +               }
> +
>                 /* caching the updated state of the high-pass filter */
>                 st->hpf_3db_freq_idx = hpf_idx;
>                 /* retrieving the current state of the low-pass filter */
>                 lpf_idx = st->lpf_3db_freq_idx;
> -               return adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> +               ret = adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> +               break;
> +
> +       default:
> +               ret = -EINVAL;
> +               break;
>         }
>
> -       return -EINVAL;
> +err_release:
> +       iio_device_release_direct_mode(indio_dev);
> +       return ret;
>  }

...

> +       val = (state ? ADXRS290_SYNC(ADXRS290_DATA_RDY_OUT) : 0);

Purpose of outer parentheses?

...

> +static int adxrs290_probe_trigger(struct iio_dev *indio_dev)
> +{
> +       struct adxrs290_state *st = iio_priv(indio_dev);
> +       int ret;
> +
> +       if (!st->spi->irq) {
> +               dev_info(&st->spi->dev, "no irq, using polling\n");
> +               return 0;
> +       }
> +
> +       st->dready_trig = devm_iio_trigger_alloc(&st->spi->dev,
> +                                                "%s-dev%d",
> +                                                indio_dev->name,
> +                                                indio_dev->id);
> +       if (!st->dready_trig)
> +               return -ENOMEM;
> +
> +       st->dready_trig->dev.parent = &st->spi->dev;
> +       st->dready_trig->ops = &adxrs290_trigger_ops;
> +       iio_trigger_set_drvdata(st->dready_trig, indio_dev);
> +
> +       ret = devm_request_irq(&st->spi->dev, st->spi->irq,
> +                              &iio_trigger_generic_data_rdy_poll,
> +                              IRQF_ONESHOT,
> +                              "adxrs290_irq", st->dready_trig);
> +       if (ret < 0) {

> +               dev_err(&st->spi->dev, "request irq %d failed\n", st->spi->irq);
> +               return ret;

return dev_err_probe(...);

> +       }
> +
> +       ret = devm_iio_trigger_register(&st->spi->dev, st->dready_trig);
> +       if (ret) {

> +               dev_err(&st->spi->dev, "iio trigger register failed\n");
> +               return ret;

return dev_err_probe(...);

> +       }
> +
> +       indio_dev->trig = iio_trigger_get(st->dready_trig);
> +
> +       return 0;
> +}

...

> +       ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
> +                                             &iio_pollfunc_store_time,
> +                                             &adxrs290_trigger_handler, NULL);
> +       if (ret < 0) {

> +               dev_err(&spi->dev, "iio triggered buffer setup failed\n");
> +               return ret;

return dev_err_probe(...);

> +       }

-- 
With Best Regards,
Andy Shevchenko

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