Re: [PATCH] staging: tegra-video: replace bit shifts with BIT() macro

[Luca Ceresoli]

On Tue Apr 28, 2026 at 6:33 PM CEST, Mhanna112-code wrote:
> Replace manual bit shifts with the BIT() macro to follow kernel
> coding style and improve readability.
>
> Fixes the following checkpatch warning:
>
> CHECK: Prefer using the BIT macro
>
> Signed-off-by: Marc Hanna <marchanna111@xxxxxxxxx>
> ---
>  drivers/staging/media/tegra-video/tegra20.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/media/tegra-video/tegra20.c b/drivers/staging/media/tegra-video/tegra20.c
> index eb1fc5b7e2cd..f3edca909684 100644
> --- a/drivers/staging/media/tegra-video/tegra20.c
> +++ b/drivers/staging/media/tegra-video/tegra20.c
> @@ -177,15 +177,15 @@ enum tegra_vi_out {
>  #define       CSI_SKIP_PACKET_THRESHOLD(n)		(((n) & 0xff) << 16)
>  #define TEGRA_CSI_PIXEL_STREAM_CONTROL0(n)		(0x0018 + (n) * 0x2c)
>  #define       CSI_PP_PAD_FRAME_PAD0S			(0 << 28)
> -#define       CSI_PP_PAD_FRAME_PAD1S			(1 << 28)
> +#define       CSI_PP_PAD_FRAME_PAD1S			BIT(28)
>  #define       CSI_PP_PAD_FRAME_NOPAD			(2 << 28)
>  #define       CSI_PP_HEADER_EC_ENABLE			BIT(27)
>  #define       CSI_PP_PAD_SHORT_LINE_PAD0S		(0 << 24)
> -#define       CSI_PP_PAD_SHORT_LINE_PAD1S		(1 << 24)
> +#define       CSI_PP_PAD_SHORT_LINE_PAD1S		BIT(24)
>  #define       CSI_PP_PAD_SHORT_LINE_NOPAD		(2 << 24)
>  #define       CSI_PP_EMBEDDED_DATA_EMBEDDED		BIT(20)
>  #define       CSI_PP_OUTPUT_FORMAT_ARBITRARY		(0 << 16)
> -#define       CSI_PP_OUTPUT_FORMAT_PIXEL		(1 << 16)
> +#define       CSI_PP_OUTPUT_FORMAT_PIXEL		BIT(16)
>  #define       CSI_PP_OUTPUT_FORMAT_PIXEL_REP		(2 << 16)
>  #define       CSI_PP_OUTPUT_FORMAT_STORE		(3 << 16)
>  #define       CSI_PP_VIRTUAL_CHANNEL_ID(n)		(((n) - 1) << 14)

I think this change would make code worse, not better. These look like
enum-like values for 2-bit register fields, and as such should be described
the same way for readability.

If we want to change them they should perhaps use a GENMASK or similar, but
it probably makes sense to just leave them as is. They are mostly unused
anyway.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com