Re: [PATCH 1/5] Staging: iio: cdc: ad7746: Prefer using the BIT macro

[Jonathan Cameron <jic23@kernel.org>]

On 29/12/15 11:27, Shraddha Barke wrote:
> Replace bit shifting on 1 with the BIT(x) macro
> 
> Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
Hi Shraddha,

Good to see someone looking at these rather neglected drivers ;)

Anyhow, in a few cases here you have converted a single bit write
within a larger field (2 or 3 bits) over to the BIT macro.
This makes the code harder to read so should not be done.

The rest of the changes are good!

Jonathan
> ---
>  drivers/staging/iio/cdc/ad7746.c | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
> index 2c5d277..a4ad2f1 100644
> --- a/drivers/staging/iio/cdc/ad7746.c
> +++ b/drivers/staging/iio/cdc/ad7746.c
> @@ -45,20 +45,20 @@
>  #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)
>  
>  /* 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)
Not this one.  We are writing a 1 to a 2 bit field here so BIT(5) is misleading.

>  #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)
>  
>  /* Excitation Setup Register Bit Designations (AD7746_REG_EXC_SETUP) */
>  #define AD7746_EXCSETUP_CLKCTRL		BIT(7)
> @@ -73,14 +73,14 @@
>  #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)
Again, these are different values being written to a 3 bit field
so don't mix and max.
>  #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)
>  
>  /* 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)
>  
>  /*
>