Re: [PATCH v2 2/2] iio: adc: stm32-adc: skip adc-channels setup if none is present

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 21 Apr 2023 13:35:16 +0200
Sean Nyekjaer <sean@geanix.com> wrote:

> If only adc differential channels are defined driver will fail with
> stm32-adc: probe of 48003000.adc:adc@0 failed with error -22
> 
> Fix this by skipping the initialization if no channels are defined.
> 
> This applies only to the legacy way of initializing adc channels.
> 
> Fixes: d7705f35448a ("iio: adc: stm32-adc: convert to device properties")
> Signed-off-by: Sean Nyekjaer <sean@geanix.com>

Olivier,

You gave some good feedback on v1. Please take a look to see if it
has all been addressed in v2.

Thanks,

Jonathan

> ---
> Changes since v1:
>  - Ignore extra channel for timestamps in PIO mode
>  - Use single ended count in channel creation (Thanks Olivier Moysan)
> 
>  drivers/iio/adc/stm32-adc.c | 40 ++++++++++++++++++-------------------
>  1 file changed, 20 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index 14524c1b5583..99bfe995b6f1 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -2038,6 +2038,7 @@ static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
>  	struct stm32_adc_diff_channel diff[STM32_ADC_CH_MAX];
>  	struct device *dev = &indio_dev->dev;
>  	u32 num_diff = adc->num_diff;
> +	int num_se = nchans - num_diff;
>  	int size = num_diff * sizeof(*diff) / sizeof(u32);
>  	int scan_index = 0, ret, i, c;
>  	u32 smp = 0, smps[STM32_ADC_CH_MAX], chans[STM32_ADC_CH_MAX];
> @@ -2065,28 +2066,27 @@ static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
>  		}
>  	}
>  
> -	ret = device_property_read_u32_array(dev, "st,adc-channels", chans,
> -					     nchans);
> -	if (ret)
> -		return ret;
> -
> -	for (c = 0; c < nchans; c++) {
> -		if (chans[c] >= adc_info->max_channels) {
> -			dev_err(&indio_dev->dev, "Invalid channel %d\n",
> -				chans[c]);
> -			return -EINVAL;
> -		}
> -
> -		/* Channel can't be configured both as single-ended & diff */
> -		for (i = 0; i < num_diff; i++) {
> -			if (chans[c] == diff[i].vinp) {
> -				dev_err(&indio_dev->dev, "channel %d misconfigured\n",	chans[c]);
> +	ret = device_property_read_u32_array(dev, "st,adc-channels", chans, num_se);
> +	if (ret == 0 && num_se > 0) {
> +		for (c = 0; c < num_se; c++) {
> +			if (chans[c] >= adc_info->max_channels) {
> +				dev_err(&indio_dev->dev, "Invalid channel %d\n",
> +					chans[c]);
>  				return -EINVAL;
>  			}
> +
> +			/* Channel can't be configured both as single-ended & diff */
> +			for (i = 0; i < num_diff; i++) {
> +				if (chans[c] == diff[i].vinp) {
> +					dev_err(&indio_dev->dev, "channel %d misconfigured\n",
> +						chans[c]);
> +					return -EINVAL;
> +				}
> +			}
> +			stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
> +						chans[c], 0, scan_index, false);
> +			scan_index++;
>  		}
> -		stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
> -					chans[c], 0, scan_index, false);
> -		scan_index++;
>  	}
>  
>  	if (adc->nsmps > 0) {
> @@ -2307,7 +2307,7 @@ static int stm32_adc_chan_fw_init(struct iio_dev *indio_dev, bool timestamping)
>  
>  	if (legacy)
>  		ret = stm32_adc_legacy_chan_init(indio_dev, adc, channels,
> -						 num_channels);
> +						 timestamping ? num_channels - 1 : num_channels);
>  	else
>  		ret = stm32_adc_generic_chan_init(indio_dev, adc, channels);
>  	if (ret < 0)