linux-kernel - Re: [PATCH 4/6] Staging: iio: cdc: ad7746.c: Prefer using the BIT macro

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Date:	Thu, 10 Sep 2015 07:59:38 +0200 (CEST)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	Shraddha Barke <shraddha.6596@...il.com>
cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Jonathan Cameron <jic23@...nel.org>,
	Peter Meerwald <pmeerw@...erw.net>,
	Hartmut Knaack <knaack.h@....de>, linux-kernel@...r.kernel.org,
	Julia Lawall <julia.lawall@...6.fr>
Subject: Re: [PATCH 4/6] Staging: iio: cdc: ad7746.c: Prefer using the BIT
 macro

On Thu, 10 Sep 2015, Shraddha Barke wrote:

> This patch replaces bit shifting on 1 with the BIT(x) macro
> as it's extensively used by other function in this driver.
> 
> This was done with coccinelle:
> @@ int g; @@
> 
> -(1 << g)
> +BIT(g)
> 
> Signed-off-by: Shraddha Barke <shraddha.6596@...il.com>
> ---
>  drivers/staging/iio/cdc/ad7746.c | 42 ++++++++++++++++++++--------------------
>  1 file changed, 21 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
> index e6e9eaa..e17d4e1 100644
> --- a/drivers/staging/iio/cdc/ad7746.c
> +++ b/drivers/staging/iio/cdc/ad7746.c
> @@ -46,48 +46,48 @@
>  #define AD7746_REG_VOLT_GAINL		18
>  
>  /* Status Register Bit Designations (AD7746_REG_STATUS) */
> -#define AD7746_STATUS_EXCERR		(1 << 3)
> -#define AD7746_STATUS_RDY		(1 << 2)
> -#define AD7746_STATUS_RDYVT		(1 << 1)
> -#define AD7746_STATUS_RDYCAP		(1 << 0)
> +#define AD7746_STATUS_EXCERR		BIT(3)
> +#define AD7746_STATUS_RDY		BIT(2)
> +#define AD7746_STATUS_RDYVT		BIT(1)
> +#define AD7746_STATUS_RDYCAP		BIT(0)
>  
>  /* Capacitive Channel Setup Register Bit Designations (AD7746_REG_CAP_SETUP) */
> -#define AD7746_CAPSETUP_CAPEN		(1 << 7)
> -#define AD7746_CAPSETUP_CIN2		(1 << 6) /* AD7746 only */
> -#define AD7746_CAPSETUP_CAPDIFF		(1 << 5)
> -#define AD7746_CAPSETUP_CACHOP		(1 << 0)
> +#define AD7746_CAPSETUP_CAPEN		BIT(7)
> +#define AD7746_CAPSETUP_CIN2		BIT(6) /* AD7746 only */
> +#define AD7746_CAPSETUP_CAPDIFF		BIT(5)
> +#define AD7746_CAPSETUP_CACHOP		BIT(0)

You could harmonize the indentation in this bunch.

>  /* Voltage/Temperature Setup Register Bit Designations (AD7746_REG_VT_SETUP) */
> -#define AD7746_VTSETUP_VTEN		(1 << 7)
> +#define AD7746_VTSETUP_VTEN		BIT(7)
>  #define AD7746_VTSETUP_VTMD_INT_TEMP	(0 << 5)
> -#define AD7746_VTSETUP_VTMD_EXT_TEMP	(1 << 5)
> +#define AD7746_VTSETUP_VTMD_EXT_TEMP	BIT(5)
>  #define AD7746_VTSETUP_VTMD_VDD_MON	(2 << 5)
>  #define AD7746_VTSETUP_VTMD_EXT_VIN	(3 << 5)
> -#define AD7746_VTSETUP_EXTREF		(1 << 4)
> -#define AD7746_VTSETUP_VTSHORT		(1 << 1)
> -#define AD7746_VTSETUP_VTCHOP		(1 << 0)
> +#define AD7746_VTSETUP_EXTREF		BIT(4)
> +#define AD7746_VTSETUP_VTSHORT		BIT(1)
> +#define AD7746_VTSETUP_VTCHOP		BIT(0)

It doesn't look like a good idea to use BIT here, because it is mixed with 
other things.

>  /* Excitation Setup Register Bit Designations (AD7746_REG_EXC_SETUP) */
> -#define AD7746_EXCSETUP_CLKCTRL		(1 << 7)
> -#define AD7746_EXCSETUP_EXCON		(1 << 6)
> -#define AD7746_EXCSETUP_EXCB		(1 << 5)
> -#define AD7746_EXCSETUP_NEXCB		(1 << 4)
> -#define AD7746_EXCSETUP_EXCA		(1 << 3)
> -#define AD7746_EXCSETUP_NEXCA		(1 << 2)
> +#define AD7746_EXCSETUP_CLKCTRL		BIT(7)
> +#define AD7746_EXCSETUP_EXCON		BIT(6)
> +#define AD7746_EXCSETUP_EXCB		BIT(5)
> +#define AD7746_EXCSETUP_NEXCB		BIT(4)
> +#define AD7746_EXCSETUP_EXCA		BIT(3)
> +#define AD7746_EXCSETUP_NEXCA		BIT(2)
>  #define AD7746_EXCSETUP_EXCLVL(x)	(((x) & 0x3) << 0)

Fix the alignment.

>  /* Config Register Bit Designations (AD7746_REG_CFG) */
>  #define AD7746_CONF_VTFS(x)		((x) << 6)
>  #define AD7746_CONF_CAPFS(x)		((x) << 3)
>  #define AD7746_CONF_MODE_IDLE		(0 << 0)
> -#define AD7746_CONF_MODE_CONT_CONV	(1 << 0)
> +#define AD7746_CONF_MODE_CONT_CONV	BIT(0)
>  #define AD7746_CONF_MODE_SINGLE_CONV	(2 << 0)
>  #define AD7746_CONF_MODE_PWRDN		(3 << 0)
>  #define AD7746_CONF_MODE_OFFS_CAL	(5 << 0)
>  #define AD7746_CONF_MODE_GAIN_CAL	(6 << 0)

Don't use BIT in this case.

julia

>  /* CAPDAC Register Bit Designations (AD7746_REG_CAPDACx) */
> -#define AD7746_CAPDAC_DACEN		(1 << 7)
> +#define AD7746_CAPDAC_DACEN		BIT(7)
>  #define AD7746_CAPDAC_DACP(x)		((x) & 0x7F)
>  
>  /*
> -- 
> 2.1.4
> 
> 
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