Re: [PATCH 07/10] Staging: comedi: fix BIT macro issue in das6402.c

Ian Abbott
2016-06-01T13:59:03Z

On 01/06/16 11:26, Ravishankar Karkala Mallikarjunayya wrote:
> This patch Replace all occurences of (1<<x) by BIT(x) in the file das6402.c
> to get rid of checkpatch.pl "CHECK" output "Prefer using the BIT macro"
>
> Signed-off-by: Ravishankar Karkala Mallikarjunayya <ravishankarkm32@gmail.com>
> ---
> drivers/staging/comedi/drivers/das6402.c | 56 ++++++++++++++++----------------
> 1 file changed, 28 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/staging/comedi/drivers/das6402.c b/drivers/staging/comedi/drivers/das6402.c
> index 1701294..f6319b3 100644
> --- a/drivers/staging/comedi/drivers/das6402.c
> +++ b/drivers/staging/comedi/drivers/das6402.c
[snip]
> #define DAS6402_CTRL_REG 0x09
> #define DAS6402_CTRL_SOFT_TRIG (0 << 0)
> -#define DAS6402_CTRL_EXT_FALL_TRIG (1 << 0)
> +#define DAS6402_CTRL_EXT_FALL_TRIG BIT(0)
> #define DAS6402_CTRL_EXT_RISE_TRIG (2 << 0)
> #define DAS6402_CTRL_PACER_TRIG (3 << 0)

In cases like this, where there are several values defined for a
multi-bit field, all shifted by the same amount, the 'BIT(x)' usage
makes the code more unreadable. The DAS6402_CTRL_SOFT_TRIG,
DAS6402_CTRL_EXT_FALL_TRIG, DAS6402_CTRL_EXT_RISE_TRIG, and
DAS6402_CTRL_PACER_TRIG values should all share the same style, perhaps
something like this:

#define DAS6402_CTRL_TRIG(x) ((x) << 0)
#define DAS6402_CTRL_SOFT_TRIG DAS6402_CTRL_TRIG(0)
#define DAS6402_CTRL_EXT_FALL_TRIG DAS6402_CTRL_TRIG(1)
#define DAS6402_CTRL_EXT_RISE_TRIG DAS6402_CTRL_TRIG(2)
#define DAS6402_CTRL_PACER_TRIG DAS6402_CTRL_TRIG(3)

[snip]
> #define DAS6402_MODE_REG 0x0b
> #define DAS6402_MODE_RANGE(x) ((x) << 0)
> #define DAS6402_MODE_POLLED (0 << 2)
> -#define DAS6402_MODE_FIFONEPTY (1 << 2)
> +#define DAS6402_MODE_FIFONEPTY BIT(2)
> #define DAS6402_MODE_FIFOHFULL (2 << 2)
> #define DAS6402_MODE_EOB (3 << 2)

Similarly, DAS6402_MODE_POLLED, DAS6402_MODE_FIFONEPTY,
DAS6402_MODE_FIFOHFULL, and DAS6402_MODE_EOB are all values for the same
multi-bit field, and should be defined in the same style, perhaps
something like this:

#define DAS6402_MODE_BUF(x) ((x) << 2)
#define DAS6402_MODE_BUF_POLLED DAS6402_MODE_BUF(0)
#define DAS6402_MODE_FIFONEPTY DAS6402_MODE_BUF(1)
#define DAS6402_MODE_FIFOHFULL DAS6402_MODE_BUF(2)
#define DAS6402_MODE_EOB DAS6402_MODE_BUF(3)

> -#define DAS6402_MODE_ENHANCED (1 << 4)
> -#define DAS6402_MODE_SE (1 << 5)
> -#define DAS6402_MODE_UNI (1 << 6)
> +#define DAS6402_MODE_ENHANCED BIT(4)
> +#define DAS6402_MODE_SE BIT(5)
> +#define DAS6402_MODE_UNI BIT(6)
> #define DAS6402_MODE_DMA1 (0 << 7)
> -#define DAS6402_MODE_DMA3 (1 << 7)
> +#define DAS6402_MODE_DMA3 BIT(7)

Similarly, DAS6402_MODE_DMA1 and DAS6402_MODE_DMA3 should be defined in
the same style, perhaps something like this:

#define DAS6402_MODE_DMA(x) ((x) << 7)
#define DAS6402_MODE_DMA1 DAS6402_MODE_DMA(0)
#define DAS6402_MODE_DMA3 DAS6402_MODE_DMA(1)