Re: [PATCH v2 5/8] iio: adc: ad7124: add sequencer support

Jonathan Cameron
2022-03-19T16:01:43Z

On Fri, 18 Mar 2022 18:27:19 +0200
<alexandru.tachici@analog.com> wrote:

> From: Alexandru Tachici <alexandru.tachici@analog.com>
>
> Add sequencer support for AD7124.
>
> Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
Hi Alexandru,

A few comments inline.

Thanks,

Jonathan

> ---
> drivers/iio/adc/ad7124.c | 32 +++++++++++++++++++++++++-------
> 1 file changed, 25 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
> index 428ec3e257d7..782b7cdd8ebe 100644
> --- a/drivers/iio/adc/ad7124.c
> +++ b/drivers/iio/adc/ad7124.c
> @@ -43,6 +43,8 @@
> #define AD7124_STATUS_POR_FLAG_MSK BIT(4)
>
> /* AD7124_ADC_CONTROL */
> +#define AD7124_ADC_STATUS_EN_MSK BIT(10)
> +#define AD7124_ADC_STATUS_EN(x) FIELD_PREP(AD7124_ADC_STATUS_EN_MSK, x)
> #define AD7124_ADC_CTRL_REF_EN_MSK BIT(8)
> #define AD7124_ADC_CTRL_REF_EN(x) FIELD_PREP(AD7124_ADC_CTRL_REF_EN_MSK, x)
> #define AD7124_ADC_CTRL_PWR_MSK GENMASK(7, 6)
> @@ -512,14 +514,27 @@ static int ad7124_set_channel(struct ad_sigma_delta *sd, unsigned int channel)
> return ret;
> }
>
> +static int ad7124_append_status(struct ad_sigma_delta *sd, bool append)
> +{
> + struct ad7124_state *st = container_of(sd, struct ad7124_state, sd);
> +
> + st->adc_control &= ~AD7124_ADC_STATUS_EN_MSK;
> + st->adc_control |= AD7124_ADC_STATUS_EN(append);

Generally avoid updating cached state until you know the write succeeded.
So I would operate on a local variable and if ad_sd_write_reg() succeeds
copy that back into st->adc_control.

Obviously on error it 'might' have been updated successfully and something failed
after the write, but it is probably more likely the write failed.

> +
> + return ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL, 2, st->adc_control);
> +}
> +
> static const struct ad_sigma_delta_info ad7124_sigma_delta_info = {
> .set_channel = ad7124_set_channel,
> + .append_status = ad7124_append_status,
> .set_mode = ad7124_set_mode,
> .has_registers = true,
> .addr_shift = 0,
> .read_mask = BIT(6),
> + .status_ch_mask = GENMASK(3, 0),
> .data_reg = AD7124_DATA,
> - .irq_flags = IRQF_TRIGGER_FALLING
> + .num_slots = 8,
> + .irq_flags = IRQF_TRIGGER_FALLING,
> };
>
> static int ad7124_read_raw(struct iio_dev *indio_dev,
> @@ -679,10 +694,11 @@ static int ad7124_update_scan_mode(struct iio_dev *indio_dev,
>
> for (i = 0; i < st->num_channels; i++) {
> bit_set = test_bit(i, scan_mask);
> - ret = ad7124_spi_write_mask(st, AD7124_CHANNEL(i),
> - AD7124_CHANNEL_EN_MSK,
> - AD7124_CHANNEL_EN(bit_set),
> - 2);
> + if (bit_set)
> + ret = ad7124_set_channel(&st->sd, i);

This is going to repeatedly take an release the cfg mutex. Perhaps it's worth
introducing a __ad7124_set_channel() that doesn't take the lock then take it around
this loop instead?

> + else
> + ret = ad7124_spi_write_mask(st, AD7124_CHANNEL(i), AD7124_CHANNEL_EN_MSK,
> + 0, 2);
> if (ret < 0)
> return ret;
> }
> @@ -906,12 +922,14 @@ static int ad7124_probe(struct spi_device *spi)
>
> st->chip_info = info;
>
> - ad_sd_init(&st->sd, indio_dev, spi, &ad7124_sigma_delta_info);
> -
> indio_dev->name = st->chip_info->name;
> indio_dev->modes = INDIO_DIRECT_MODE;
> indio_dev->info = &ad7124_info;
>
> + ret = ad_sd_init(&st->sd, indio_dev, spi, &ad7124_sigma_delta_info);
> + if (ret < 0)
> + return ret;
> +
> ret = ad7124_of_parse_channel_config(indio_dev, spi->dev.of_node);
> if (ret < 0)
> return ret;