linux-kernel - Re: [PATCH] iio: adc: ad_sigma_delta: fix disable

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Date: Fri, 21 Jun 2024 16:26:29 +0300
From: Alexandru Ardelean <aardelean@...libre.com>
To: Dumitru Ceclan <mitrutzceclan@...il.com>
Cc: jic23@...nel.org, dlechner@...libre.com, dumitru.ceclan@...log.com0, 
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Dumitru Ceclan <dumitru.ceclan@...log.com>
Subject: Re: [PATCH] iio: adc: ad_sigma_delta: fix disable_one callback

On Fri, Jun 21, 2024 at 3:05 PM Dumitru Ceclan <mitrutzceclan@...il.com> wrote:
>
> The ADC ad7192 is a sigma delta ADC with a sequencer that does not
> require a disable_one callback as all enable channel bits are within
> the same register.
>
> Remove the requirement of the disable_one callback for sigma delta ADCs
> with a sequencer.
>
> This patch could be squashed with the commit that it fixes from patch
> series: Add support for AD411x
>

This fix looks fine.
But, then this raises a question if this needs be to extended to the
`disable_all` and maybe `indio_dev->info->update_scan_mode` check.
And if so, how should this be handled?

For example:
drivers/iio/adc/ad7124.c:    .disable_all = ad7124_disable_all,
drivers/iio/adc/ad7173.c:    .disable_all = ad7173_disable_all,
drivers/iio/adc/ad7192.c:    .disable_all = ad7192_disable_all,
drivers/iio/adc/ad7192.c:    .disable_all = ad7192_disable_all,

And:
drivers/iio/adc/ad7124.c:    ret = ad_sd_init(&st->sd, indio_dev, spi,
&ad7124_sigma_delta_info);
drivers/iio/adc/ad7173.c:    ret = ad_sd_init(&st->sd, indio_dev, spi,
&ad7173_sigma_delta_info);
drivers/iio/adc/ad7192.c:    ret = ad_sd_init(&st->sd, indio_dev, spi,
st->chip_info->sigma_delta_info);
drivers/iio/adc/ad7780.c:    ad_sd_init(&st->sd, indio_dev, spi,
&ad7780_sigma_delta_info);
drivers/iio/adc/ad7791.c:    ad_sd_init(&st->sd, indio_dev, spi,
&ad7791_sigma_delta_info);
drivers/iio/adc/ad7793.c:    ad_sd_init(&st->sd, indio_dev, spi,
&ad7793_sigma_delta_info);

At least the ad7791.c & ad7793.c drivers support parts with more than
1 channel, and there does not seem to be any `disable_all` hook
defined (at least in iio/testing).
I have not gone too deep with `indio_dev->info->update_scan_mode`, but
it would be worth to do a check there as well


> Fixes: a25a0aab2187 ("iio: adc: ad_sigma_delta: add disable_one callback")
> Signed-off-by: Dumitru Ceclan <dumitru.ceclan@...log.com>
> ---
>  drivers/iio/adc/ad_sigma_delta.c | 5 -----
>  1 file changed, 5 deletions(-)
>
> diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
> index d6b5fca034a0..8c062b0d26e3 100644
> --- a/drivers/iio/adc/ad_sigma_delta.c
> +++ b/drivers/iio/adc/ad_sigma_delta.c
> @@ -672,11 +672,6 @@ int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
>                         dev_err(&spi->dev, "ad_sigma_delta_info lacks disable_all().\n");
>                         return -EINVAL;
>                 }
> -
> -               if (!info->disable_one) {
> -                       dev_err(&spi->dev, "ad_sigma_delta_info lacks disable_one().\n");
> -                       return -EINVAL;
> -               }
>         }
>
>         if (info->irq_line)
> --
> 2.43.0
>
>