linux-kernel - Re: [PATCH 2/4] iio: dac: mcp4922: get and enable vdd regulator

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Date:   Fri, 7 Apr 2023 18:44:20 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Nicolas Frattaroli <frattaroli.nicolas@...il.com>
Cc:     Lars-Peter Clausen <lars@...afoo.de>, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] iio: dac: mcp4922: get and enable vdd regulator

On Wed,  5 Apr 2023 16:01:12 +0200
Nicolas Frattaroli <frattaroli.nicolas@...il.com> wrote:

> The MCP4922 family of chips has a vdd power input, which we
> model in our device tree binding for it. The driver should get
> and enable the vdd regulator as is appropriate.
> 
> Signed-off-by: Nicolas Frattaroli <frattaroli.nicolas@...il.com>

If, before doing this you add a patch using devm for all the
unwinding currently being done by hand in remove() you can
simplify this further use devm_regulator_get_enable()
(Note you can only do that for this regulator as we never touch it
 after enable - more complex handling needed for the vref one as
 described in review of patch 4.)

That conversion patch is pretty simple, so whilst I don't like asking
people to implement extra features, in this case the simplifications
to what you are doing here make that precusor work justified

Jonathan


> ---
>  drivers/iio/dac/mcp4922.c | 24 ++++++++++++++++++++----
>  1 file changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/dac/mcp4922.c b/drivers/iio/dac/mcp4922.c
> index da4327624d45..0b9458cbbcff 100644
> --- a/drivers/iio/dac/mcp4922.c
> +++ b/drivers/iio/dac/mcp4922.c
> @@ -31,6 +31,7 @@ struct mcp4922_state {
>  	unsigned int value[MCP4922_NUM_CHANNELS];
>  	unsigned int vref_mv;
>  	struct regulator *vref_reg;
> +	struct regulator *vdd_reg;
>  	u8 mosi[2] __aligned(IIO_DMA_MINALIGN);
>  };
>  
> @@ -148,10 +149,23 @@ static int mcp4922_probe(struct spi_device *spi)
>  	if (ret < 0) {
>  		dev_err(&spi->dev, "Failed to read vref regulator: %d\n",
>  				ret);
> -		goto error_disable_reg;
> +		goto error_disable_vref_reg;
>  	}
>  	state->vref_mv = ret / 1000;
>  
> +	state->vdd_reg = devm_regulator_get(&spi->dev, "vdd");
> +	if (IS_ERR(state->vdd_reg)) {
> +		ret = dev_err_probe(&spi->dev, PTR_ERR(state->vdd_reg),
> +				    "vdd regulator not specified\n");
> +		goto error_disable_vref_reg;
> +	}
> +	ret = regulator_enable(state->vdd_reg);
> +	if (ret) {
> +		dev_err(&spi->dev, "Failed to enable vdd regulator: %d\n",
> +			ret);
> +		goto error_disable_vref_reg;
> +	}
> +
>  	spi_set_drvdata(spi, indio_dev);
>  	id = spi_get_device_id(spi);
>  	indio_dev->info = &mcp4922_info;
> @@ -167,12 +181,13 @@ static int mcp4922_probe(struct spi_device *spi)
>  	if (ret) {
>  		dev_err(&spi->dev, "Failed to register iio device: %d\n",
>  				ret);
> -		goto error_disable_reg;
> +		goto error_disable_vdd_reg;
>  	}
>  
>  	return 0;
> -
> -error_disable_reg:
> +error_disable_vdd_reg:
> +	regulator_disable(state->vdd_reg);
> +error_disable_vref_reg:
>  	regulator_disable(state->vref_reg);
>  
>  	return ret;
> @@ -185,6 +200,7 @@ static void mcp4922_remove(struct spi_device *spi)
>  
>  	iio_device_unregister(indio_dev);
>  	state = iio_priv(indio_dev);
> +	regulator_disable(state->vdd_reg);
>  	regulator_disable(state->vref_reg);
>  }
>