linux-kernel - Re: [PATCH v2 03/10] iio: adc: ad7476: Use mV for internal reference

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Message-ID: <qxgzakplhavmxk5ri6yghm3fkq33cbneclqrbwdlyviyzcadmx@cilvs5lb7kwp>
Date: Thu, 7 Aug 2025 13:31:29 +0100
From: Nuno Sá <noname.nuno@...il.com>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>, 
	Lars-Peter Clausen <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>, 
	Jonathan Cameron <jic23@...nel.org>, David Lechner <dlechner@...libre.com>, 
	Nuno Sá <nuno.sa@...log.com>, Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, linux-iio@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 03/10] iio: adc: ad7476: Use mV for internal reference

On Thu, Aug 07, 2025 at 12:34:18PM +0300, Matti Vaittinen wrote:
> The ad7476 supports some ICs with an internal reference voltage. For
> those ICs the reference voltage has been hard-coded as micro volts, but
> the value which is later used in code needs to be milli volts. This
> results the need to divide hard coded voltage by 1000 before using it.
> 
> Simplify code by changing the hard-coded voltage to millivolts and by
> dropping the division.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
> ---
> Revision history:
>  v1 => :
>  - No changes
> ---

Makes sense

Reviewed-by: Nuno Sá <nuno.sa@...log.com>

>  drivers/iio/adc/ad7476.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
> index f117aafd8fad..7b6d36999afc 100644
> --- a/drivers/iio/adc/ad7476.c
> +++ b/drivers/iio/adc/ad7476.c
> @@ -27,7 +27,7 @@
>  struct ad7476_state;
>  
>  struct ad7476_chip_info {
> -	unsigned int			int_vref_uv;
> +	unsigned int			int_vref_mv;
>  	struct iio_chan_spec		channel[2];
>  	/* channels used when convst gpio is defined */
>  	struct iio_chan_spec		convst_channel[2];
> @@ -172,7 +172,7 @@ static const struct ad7476_chip_info ad7091r_chip_info = {
>  	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
>  	.convst_channel[0] = AD7091R_CONVST_CHAN(12),
>  	.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> -	.int_vref_uv = 2500000,
> +	.int_vref_mv = 2500,
>  	.has_vref = true,
>  	.reset = ad7091_reset,
>  };
> @@ -229,7 +229,7 @@ static const struct ad7476_chip_info ad7475_chip_info = {
>  static const struct ad7476_chip_info ad7495_chip_info = {
>  	.channel[0] = AD7476_CHAN(12),
>  	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> -	.int_vref_uv = 2500000,
> +	.int_vref_mv = 2500,
>  	.has_vdrive = true,
>  };
>  
> @@ -295,7 +295,7 @@ static int ad7476_probe(struct spi_device *spi)
>  		return -ENODEV;
>  
>  	/* Use VCC for reference voltage if vref / internal vref aren't used */
> -	if (!st->chip_info->int_vref_uv && !st->chip_info->has_vref) {
> +	if (!st->chip_info->int_vref_mv && !st->chip_info->has_vref) {
>  		ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vcc");
>  		if (ret < 0)
>  			return ret;
> @@ -310,7 +310,7 @@ static int ad7476_probe(struct spi_device *spi)
>  		ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vref");
>  		if (ret < 0) {
>  			/* Vref is optional if a device has an internal reference */
> -			if (!st->chip_info->int_vref_uv || ret != -ENODEV)
> +			if (!st->chip_info->int_vref_mv || ret != -ENODEV)
>  				return ret;
>  		} else {
>  			st->scale_mv = ret / 1000;
> @@ -318,7 +318,7 @@ static int ad7476_probe(struct spi_device *spi)
>  	}
>  
>  	if (!st->scale_mv)
> -		st->scale_mv = st->chip_info->int_vref_uv / 1000;
> +		st->scale_mv = st->chip_info->int_vref_mv;
>  
>  	if (st->chip_info->has_vdrive) {
>  		ret = devm_regulator_get_enable(&spi->dev, "vdrive");
> -- 
> 2.50.1
>