linux-kernel - Re: [PATCH v2 1/2] staging: iio: ad7780: check if ad778x before gain update

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Date:   Thu, 8 Nov 2018 19:26:37 +0100
From:   Tomasz Duszynski <tduszyns@...il.com>
To:     Giuliano Belinassi <giuliano.belinassi@...il.com>, lars@...afoo.de,
        Michael.Hennerich@...log.com, jic23@...nel.org, knaack.h@....de,
        pmeerw@...erw.net, gregkh@...uxfoundation.org, renatogeh@...il.com
Cc:     linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org, kernel-usp@...glegroups.com
Subject: Re: [PATCH v2 1/2] staging: iio: ad7780: check if ad778x before gain
 update

Hi Giuliano,

Comment inline.

On 11/8/18 2:03 PM, Giuliano Belinassi wrote:
> Only the ad778x have the 'gain' status bit. Check it before updating
> through a new variable is_ad778x in chip_info.
>
> Signed-off-by: Giuliano Belinassi <giuliano.belinassi@....br>
> ---
> Changes in v2:
> 	- Squashed is_ad778x declaration commit with the ad778x checkage
> 	- Changed is_ad778x type to bool
>  
>  drivers/staging/iio/adc/ad7780.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/iio/adc/ad7780.c b/drivers/staging/iio/adc/ad7780.c
> index 91e016d534ed..9ec2b002539e 100644
> --- a/drivers/staging/iio/adc/ad7780.c
> +++ b/drivers/staging/iio/adc/ad7780.c
> @@ -35,6 +35,7 @@ struct ad7780_chip_info {
>  	struct iio_chan_spec	channel;
>  	unsigned int		pattern_mask;
>  	unsigned int		pattern;
> +	bool			is_ad778x;
>  };
>  
>  struct ad7780_state {
> @@ -113,10 +114,12 @@ static int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
>  	    ((raw_sample & chip_info->pattern_mask) != chip_info->pattern))
>  		return -EIO;
>  
> -	if (raw_sample & AD7780_GAIN)
> -		st->gain = 1;
> -	else
> -		st->gain = 128;
> +	if (chip_info->is_ad778x) {
> +		if (raw_sample & AD7780_GAIN)
> +			st->gain = 1;
> +		else
> +			st->gain = 128;
> +	}

Just some random though. Instead of introducing extra level of indentation you
can simply check whether is_ad778x is asserted and simply return.

>  
>  	return 0;
>  }
> @@ -135,21 +138,25 @@ static const struct ad7780_chip_info ad7780_chip_info_tbl[] = {
>  		.channel = AD7780_CHANNEL(12, 24),
>  		.pattern = 0x5,
>  		.pattern_mask = 0x7,
> +		.is_ad778x = false,

Any reason for setting this explicitly? That's going to be false anyway.

>  	},
>  	[ID_AD7171] = {
>  		.channel = AD7780_CHANNEL(16, 24),
>  		.pattern = 0x5,
>  		.pattern_mask = 0x7,
> +		.is_ad778x = false,
>  	},
>  	[ID_AD7780] = {
>  		.channel = AD7780_CHANNEL(24, 32),
>  		.pattern = 0x1,
>  		.pattern_mask = 0x3,
> +		.is_ad778x = true,
>  	},
>  	[ID_AD7781] = {
>  		.channel = AD7780_CHANNEL(20, 32),
>  		.pattern = 0x1,
>  		.pattern_mask = 0x3,
> +		.is_ad778x = true,
>  	},
>  };
>