Re: [PATCH v2] iio: adc: ad7173: fix num_slots

[David Lechner <dlechner@baylibre.com>]

On 7/4/25 11:21 AM, David Lechner wrote:
> Fix the num_slots value for most chips in the ad7173 driver. The correct
> value is the number of CHANNELx registers on the chip.
> 
> In commit 4310e15b3140 ("iio: adc: ad7173: don't make copy of
> ad_sigma_delta_info struct"), we refactored struct ad_sigma_delta_info
> to be static const data instead of being dynamically populated during
> driver probe. However, there was an existing bug in commit 76a1e6a42802
> ("iio: adc: ad7173: add AD7173 driver") where num_slots was incorrectly
> set to the number of CONFIGx registers instead of the number of
> CHANNELx registers. This bug was partially propagated to the refactored
> code in that the 16-channel chips were only given 8 slots instead of
> 16 although we did managed to fix the 8-channel chips and one of the
> 4-channel chips in that commit. However, we botched two of the 4-channel
> chips and ended up incorrectly giving them 8 slots during the
> refactoring.
> 
> This patch fixes that mistake on the 4-channel chips and also
> corrects the 16-channel chips to have 16 slots.
> 
> Fixes: 4310e15b3140 ("iio: adc: ad7173: don't make copy of ad_sigma_delta_info struct")
> Signed-off-by: David Lechner <dlechner@baylibre.com>
> ---
> Changes in v2:
> - Improve commit message.
> - Link to v1: https://lore.kernel.org/r/20250703-iio-adc-ad7173-fix-num_slots-on-most-chips-v1-1-326c5d113e15@baylibre.com
> ---
>  drivers/iio/adc/ad7173.c | 37 +++++++++++++++++++++++++++----------
>  1 file changed, 27 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7173.c b/drivers/iio/adc/ad7173.c
> index dd9fa35555c79ead5a1b88d1dc6cc3db122502be..9c197cea11eb955becf4b9b97246379fa9c5da13 100644
> --- a/drivers/iio/adc/ad7173.c
> +++ b/drivers/iio/adc/ad7173.c
> @@ -771,10 +771,27 @@ static const struct ad_sigma_delta_info ad7173_sigma_delta_info_8_slots = {
>  	.num_slots = 8,
>  };
>  
> +static const struct ad_sigma_delta_info ad7173_sigma_delta_info_16_slots = {
> +	.set_channel = ad7173_set_channel,
> +	.append_status = ad7173_append_status,
> +	.disable_all = ad7173_disable_all,
> +	.disable_one = ad7173_disable_one,
> +	.set_mode = ad7173_set_mode,
> +	.has_registers = true,
> +	.has_named_irqs = true,

> +	.supports_spi_offload = true,

Well drat, I was too quick with the update and the bots [1] noticed that
this conflicts with the in-flight patch that added this field [2].

I guess we can drop this one line, but then the other patch will wait
until this fix makes its way back into the togreg/testing branches.

[1]: https://lore.kernel.org/linux-iio/202507050018.iWEJiG04-lkp@intel.com/
[2]: https://lore.kernel.org/linux-iio/20250701-iio-adc-ad7173-add-spi-offload-support-v3-12-42abb83e3dac@baylibre.com/

> +	.addr_shift = 0,
> +	.read_mask = BIT(6),
> +	.status_ch_mask = GENMASK(3, 0),
> +	.data_reg = AD7173_REG_DATA,
> +	.num_resetclks = 64,
> +	.num_slots = 16,
> +};
> +