linux-kernel - Re: [PATCH v4 09/15] iio: adc: ad7091r: Enable internal vref if external vref is not supplied

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Message-ID: <20231217154142.191ba69b@jic23-huawei>
Date: Sun, 17 Dec 2023 15:41:42 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Marcelo Schmitt <marcelo.schmitt@...log.com>
Cc: <apw@...onical.com>, <joe@...ches.com>, <dwaipayanray1@...il.com>,
 <lukas.bulwahn@...il.com>, <paul.cercueil@...log.com>,
 <Michael.Hennerich@...log.com>, <lars@...afoo.de>, <robh+dt@...nel.org>,
 <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
 <dan.carpenter@...aro.org>, <dlechner@...libre.com>,
 <marcelo.schmitt1@...il.com>, <linux-iio@...r.kernel.org>,
 <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 09/15] iio: adc: ad7091r: Enable internal vref if
 external vref is not supplied

On Sat, 16 Dec 2023 14:49:07 -0300
Marcelo Schmitt <marcelo.schmitt@...log.com> wrote:

> The ADC needs a voltage reference to work correctly.
> Enable AD7091R internal voltage reference if no external vref is supplied.
> 
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@...log.com>
This one sounds to me like it should have a fixes tag and be
much earlier in the set to perhaps simplify backports.

Jonathan

> ---
>  drivers/iio/adc/ad7091r-base.c | 7 +++++++
>  drivers/iio/adc/ad7091r-base.h | 1 +
>  2 files changed, 8 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad7091r-base.c b/drivers/iio/adc/ad7091r-base.c
> index aead72ef55b6..9d0b489966f5 100644
> --- a/drivers/iio/adc/ad7091r-base.c
> +++ b/drivers/iio/adc/ad7091r-base.c
> @@ -217,7 +217,14 @@ int ad7091r_probe(struct device *dev, const struct ad7091r_init_info *init_info,
>  	if (IS_ERR(st->vref)) {
>  		if (PTR_ERR(st->vref) == -EPROBE_DEFER)
>  			return -EPROBE_DEFER;
> +
>  		st->vref = NULL;
> +		/* Enable internal vref */
> +		ret = regmap_update_bits(st->map, AD7091R_REG_CONF,
> +					 AD7091R_REG_CONF_INT_VREF, BIT(0));
> +		if (ret)
> +			return dev_err_probe(st->dev, ret,
> +					     "Error on enable internal reference\n");
>  	} else {
>  		ret = regulator_enable(st->vref);
>  		if (ret)
> diff --git a/drivers/iio/adc/ad7091r-base.h b/drivers/iio/adc/ad7091r-base.h
> index 81b8a4bbb929..9cfb362a00a4 100644
> --- a/drivers/iio/adc/ad7091r-base.h
> +++ b/drivers/iio/adc/ad7091r-base.h
> @@ -20,6 +20,7 @@
>  #define AD7091R_REG_CH_HYSTERESIS(ch) ((ch) * 3 + 6)
>  
>  /* AD7091R_REG_CONF */
> +#define AD7091R_REG_CONF_INT_VREF	BIT(0)
>  #define AD7091R_REG_CONF_ALERT_EN	BIT(4)
>  #define AD7091R_REG_CONF_AUTO		BIT(8)
>  #define AD7091R_REG_CONF_CMD		BIT(10)