linux-kernel - Re: [PATCH v2] iio: adc: ad7606: move 'val' pointer to ad7606_scan

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Message-ID: <20240817155642.6ad2fa73@jic23-huawei>
Date: Sat, 17 Aug 2024 15:56:42 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Alexandru Ardelean <aardelean@...libre.com>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
 Michael.Hennerich@...log.com, lars@...afoo.de, gstols@...libre.com,
 nuno.sa@...log.com
Subject: Re: [PATCH v2] iio: adc: ad7606: move 'val' pointer to
 ad7606_scan_direct()

On Sat, 17 Aug 2024 17:36:47 +0300
Alexandru Ardelean <aardelean@...libre.com> wrote:

> The ad7606_scan_direct() function returns 'int', which is fine for 16-bit
> samples.
> But when going to 18-bit samples, these need to be implemented as 32-bit
> (or int) type.
> 
> In that case when getting samples (which can be negative), we'd get random
> error codes.
> So, the easiest thing is to just move the 'val' pointer to
> 'ad7606_scan_direct()'. This doesn't qualify as a fix, it's just a
> preparation for 18-bit ADCs (of the AD7606 family).

Send it at the start of that series then so as not to confuse me :)

> 
> Signed-off-by: Alexandru Ardelean <aardelean@...libre.com>
> ---
>  drivers/iio/adc/ad7606.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
> index dba1f28782e4..68481e97e50a 100644
> --- a/drivers/iio/adc/ad7606.c
> +++ b/drivers/iio/adc/ad7606.c
> @@ -138,7 +138,8 @@ static irqreturn_t ad7606_trigger_handler(int irq, void *p)
>  	return IRQ_HANDLED;
>  }
>  
> -static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
> +static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
> +			      int *val)
>  {
>  	struct ad7606_state *st = iio_priv(indio_dev);
>  	int ret;
> @@ -153,7 +154,7 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
>  
>  	ret = ad7606_read_samples(st);
>  	if (ret == 0)
> -		ret = st->data[ch];
> +		*val = (short)st->data[ch];
I'd rather see a sign_extend32() for that seeing as you are touching the code.
obviously it's the same thing but nicer to read!
>  
>  error_ret:
>  	gpiod_set_value(st->gpio_convst, 0);
> @@ -173,10 +174,9 @@ static int ad7606_read_raw(struct iio_dev *indio_dev,
>  	switch (m) {
>  	case IIO_CHAN_INFO_RAW:
>  		iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
> -			ret = ad7606_scan_direct(indio_dev, chan->address);
> +			ret = ad7606_scan_direct(indio_dev, chan->address, val);
>  			if (ret < 0)
>  				return ret;
> -			*val = (short) ret;
>  			return IIO_VAL_INT;
>  		}
>  		unreachable();