linux-kernel - Re: [PATCH V6 7/7] iio: adc: Add a common read function for PMIC5 and PMIC7

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Date:   Sun, 31 May 2020 11:52:24 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Jishnu Prakash <jprakash@...eaurora.org>
Cc:     agross@...nel.org, bjorn.andersson@...aro.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        mka@...omium.org, linus.walleij@...aro.org,
        Jonathan.Cameron@...wei.com, andy.shevchenko@...il.com,
        amit.kucheria@...durent.com, smohanad@...eaurora.org,
        kgunda@...eaurora.org, aghayal@...eaurora.org,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-arm-msm@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH V6 7/7] iio: adc: Add a common read function for PMIC5
 and PMIC7

On Thu, 28 May 2020 22:24:29 +0530
Jishnu Prakash <jprakash@...eaurora.org> wrote:

> Add a common function used for read_raw callback for both PMIC5
> and PMIC7 ADCs.
> 
> Signed-off-by: Jishnu Prakash <jprakash@...eaurora.org>

Hmm. I'm not completely sold on this one.   Suggestions below.

Jonathan


> ---
>  drivers/iio/adc/qcom-spmi-adc5.c | 53 +++++++++++++++++++---------------------
>  1 file changed, 25 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/iio/adc/qcom-spmi-adc5.c b/drivers/iio/adc/qcom-spmi-adc5.c
> index 0f9af66..fe49741 100644
> --- a/drivers/iio/adc/qcom-spmi-adc5.c
> +++ b/drivers/iio/adc/qcom-spmi-adc5.c
> @@ -449,6 +449,13 @@ static int adc7_do_conversion(struct adc5_chip *adc,
>  	return ret;
>  }
>  
> +struct adc_do_conversion {
> +	int (*adc_do_conversion)(struct adc5_chip *adc,
> +			struct adc5_channel_prop *prop,
> +			struct iio_chan_spec const *chan,
> +			u16 *data_volt, u16 *data_cur);

Why use a structure for this? It's just a function pointer.
If they form is too long you can always use a typedef.

This is fine if you have other stuff coming shortly that will add
to this structure but for now it's just a bit confusing.

Directly passing the function pointer will reduce the amount
of coded added here and make the argument in favour of refactoring
rather stronger.


> +};
> +
>  static irqreturn_t adc5_isr(int irq, void *dev_id)
>  {
>  	struct adc5_chip *adc = dev_id;
> @@ -487,9 +494,9 @@ static int adc7_of_xlate(struct iio_dev *indio_dev,
>  	return -EINVAL;
>  }
>  
> -static int adc5_read_raw(struct iio_dev *indio_dev,
> +static int adc_read_raw_common(struct iio_dev *indio_dev,
>  			 struct iio_chan_spec const *chan, int *val, int *val2,
> -			 long mask)
> +			 long mask, struct adc_do_conversion do_conv)
>  {
>  	struct adc5_chip *adc = iio_priv(indio_dev);
>  	struct adc5_channel_prop *prop;
> @@ -500,8 +507,8 @@ static int adc5_read_raw(struct iio_dev *indio_dev,
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_PROCESSED:
> -		ret = adc5_do_conversion(adc, prop, chan,
> -				&adc_code_volt, &adc_code_cur);
> +		ret = do_conv.adc_do_conversion(adc, prop, chan,
> +					&adc_code_volt, &adc_code_cur);
>  		if (ret)
>  			return ret;
>  
> @@ -518,36 +525,26 @@ static int adc5_read_raw(struct iio_dev *indio_dev,
>  	}
>  }
>  
> -static int adc7_read_raw(struct iio_dev *indio_dev,
> +static int adc5_read_raw(struct iio_dev *indio_dev,
>  			 struct iio_chan_spec const *chan, int *val, int *val2,
>  			 long mask)
>  {
> -	struct adc5_chip *adc = iio_priv(indio_dev);
> -	struct adc5_channel_prop *prop;
> -	u16 adc_code_volt, adc_code_cur;
> -	int ret;
> -
> -	prop = &adc->chan_props[chan->address];
> -
> -	switch (mask) {
> -	case IIO_CHAN_INFO_PROCESSED:
> -		ret = adc7_do_conversion(adc, prop, chan,
> -					&adc_code_volt, &adc_code_cur);
> -		if (ret)
> -			return ret;
> +	struct adc_do_conversion do_conv;
>  
> -		ret = qcom_adc5_hw_scale(prop->scale_fn_type,
> -			&adc5_prescale_ratios[prop->prescale],
> -			adc->data,
> -			adc_code_volt, val);
> +	do_conv.adc_do_conversion = adc5_do_conversion;
> +	return adc_read_raw_common(indio_dev, chan, val, val2,
> +				mask, do_conv);
> +}
>  
> -		if (ret)
> -			return ret;
> +static int adc7_read_raw(struct iio_dev *indio_dev,
> +			 struct iio_chan_spec const *chan, int *val, int *val2,
> +			 long mask)
> +{
> +	struct adc_do_conversion do_conv;
>  
> -		return IIO_VAL_INT;
> -	default:
> -		return -EINVAL;
> -	}
> +	do_conv.adc_do_conversion = adc7_do_conversion;
> +	return adc_read_raw_common(indio_dev, chan, val, val2,
> +				mask, do_conv);
>  }
>  
>  static const struct iio_info adc5_info = {