linux-kernel - Re: [PATCH] iio: adc: ad4000: don't use shift

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Message-ID: <aGVGTn3zFV1CuSQp@debian-BULLSEYE-live-builder-AMD64>
Date: Wed, 2 Jul 2025 11:46:38 -0300
From: Marcelo Schmitt <marcelo.schmitt1@...il.com>
To: David Lechner <dlechner@...libre.com>
Cc: Marcelo Schmitt <marcelo.schmitt@...log.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Michael Hennerich <Michael.Hennerich@...log.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Nuno Sá <nuno.sa@...log.com>,
	Andy Shevchenko <andy@...nel.org>, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: adc: ad4000: don't use shift_right()

On 07/02, David Lechner wrote:
> Drop use of shift_right() macro for unsigned value. The shift_right()
> macro is intended for signed values and is not needed for unsigned
> values.
> 
> This was found by a static analysis tool [1].
> 
> Link: https://github.com/analogdevicesinc/linux/pull/2831/files#diff-c14a34a6492576d22e7192cc0f61ad0083190aeb627191596fe12462f0c6f21aR557 [1]
> Signed-off-by: David Lechner <dlechner@...libre.com>
> ---
Reviewed-by: Marcelo Schmitt <marcelo.schmitt@...log.com>

>  drivers/iio/adc/ad4000.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/ad4000.c b/drivers/iio/adc/ad4000.c
> index 5609a7845b6f50b5818613170df6b234f8f0c496..fd3d79fca78581e51bb904d0bcfeda3d3663ea25 100644
> --- a/drivers/iio/adc/ad4000.c
> +++ b/drivers/iio/adc/ad4000.c
> @@ -554,7 +554,7 @@ static void ad4000_fill_scale_tbl(struct ad4000_state *st,
>  	val = mult_frac(st->vref_mv, MICRO, st->gain_milli);
>  
>  	/* Would multiply by NANO here but we multiplied by extra MILLI */
> -	tmp2 = shift_right((u64)val * MICRO, scale_bits);
> +	tmp2 = (u64)val * MICRO >> scale_bits;
>  	tmp0 = div_s64_rem(tmp2, NANO, &tmp1);
>  
>  	/* Store scale for when span compression is disabled */
> 
> ---
> base-commit: 6742eff60460e77158d4f1b233f17e0345c9e66a
> change-id: 20250702-iio-adc-ad4000-don-t-use-shift_right-bda6e41152b6
> 
> Best regards,
> -- 
> David Lechner <dlechner@...libre.com>
> 
>