Re: [PATCH v2 1/3] iio: gyro: adxrs290: Add triggered buffer support

[Andy Shevchenko]

On Thu, Sep 3, 2020 at 4:10 PM Nishant Malpani <nish.malpani25@xxxxxxxxx> 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;
> +
> +       if (st->mode == mode) {

> +               ret = 0;
> +               goto done;

Unlocking the not locked mutex is not good. Have you followed the
Submitting Patches Checklist? It in particular suggests few debug
options, like LOCKDEP, to be enabled.

> +       }
> +
> +       mutex_lock(&st->lock);
> +
> +       ret = spi_w8r8(st->spi, ADXRS290_READ_REG(ADXRS290_REG_POWER_CTL));
> +       if (ret < 0)
> +               goto done;
> +
> +       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:

Much better to call it out_unlock. It will help eliminate the mistakes
like above.

> +       mutex_unlock(&st->lock);
> +       return ret;
> +}

...


What about

  ret = -EINVAL;

>         switch (mask) {
>         case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
>                 lpf_idx = adxrs290_find_match(adxrs290_lpf_3db_freq_hz_table,
>                                               ARRAY_SIZE(adxrs290_lpf_3db_freq_hz_table),
>                                               val, val2);
> -               if (lpf_idx < 0)
> -                       return -EINVAL;

> +               if (lpf_idx < 0) {

> +                       ret = -EINVAL;
> +                       break;
> +               }

Simple
  break;

and so on?

> +
>                 /* caching the updated state of the low-pass filter */
>                 st->lpf_3db_freq_idx = lpf_idx;
>                 /* retrieving the current state of the high-pass filter */
>                 hpf_idx = st->hpf_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;
> +
>         case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
>                 hpf_idx = adxrs290_find_match(adxrs290_hpf_3db_freq_hz_table,
>                                               ARRAY_SIZE(adxrs290_hpf_3db_freq_hz_table),
>                                               val, val2);
> -               if (hpf_idx < 0)
> -                       return -EINVAL;
> +               if (hpf_idx < 0) {
> +                       ret = -EINVAL;
> +                       break;
> +               }
> +
>                 /* 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;
> +       iio_device_release_direct_mode(indio_dev);
> +       return ret;
>  }

...

> +static irqreturn_t adxrs290_trigger_handler(int irq, void *p)
> +{

> +       /* exercise a bulk data capture starting from reg DATAX0... */
> +       ret = spi_write_then_read(st->spi, &tx, sizeof(tx), st->buffer.channels,
> +                                 sizeof(st->buffer.channels));
> +       if (ret < 0)
> +               goto done;
> +
> +       iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
> +                                          pf->timestamp);
> +
> +done:

out_unlock_notify:

> +       mutex_unlock(&st->lock);
> +       iio_trigger_notify_done(indio_dev->trig);
> +
> +       return IRQ_HANDLED;
> +}

...

> +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;
> +       }

Wouldn't it be better to have this check outside of the function?
And taking this into account...

> +}

...

> +       ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
> +                                             &iio_pollfunc_store_time,
> +                                             &adxrs290_trigger_handler, NULL);
> +       if (ret < 0)
> +               return dev_err_probe(&spi->dev, ret,
> +                                    "iio triggered buffer setup failed\n");

...do you really have to set up a trigger buffer w/o trigger being probed?

> +       ret = adxrs290_probe_trigger(indio_dev);
> +       if (ret < 0)
> +               return ret;

-- 
With Best Regards,
Andy Shevchenko