staging: media: tegra-video: use BIT() macro instead of shift

[PATCH] staging: media: tegra-video: use BIT() macro instead of shift

Posted by A.T. Jefferies 2 months, 2 weeks ago

Replace two instances of (1 << X) with BIT(X) in tegra20.c to follow
kernel coding style guidelines and improve clarity. The BIT() macro
also ensures proper type handling for larger shifts.

Signed-off-by: A.T. Jefferies <alextjefferies@gmail.com>
---
 drivers/staging/media/tegra-video/tegra20.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/media/tegra-video/tegra20.c b/drivers/staging/media/tegra-video/tegra20.c
index 7b8f8f810b35..1473f1b1f203 100644
--- a/drivers/staging/media/tegra-video/tegra20.c
+++ b/drivers/staging/media/tegra-video/tegra20.c
@@ -42,7 +42,7 @@
 #define       VI_INPUT_BT656				BIT(25)
 #define       VI_INPUT_YUV_INPUT_FORMAT_SFT		8  /* bits [9:8] */
 #define       VI_INPUT_YUV_INPUT_FORMAT_UYVY		(0 << VI_INPUT_YUV_INPUT_FORMAT_SFT)
-#define       VI_INPUT_YUV_INPUT_FORMAT_VYUY		(1 << VI_INPUT_YUV_INPUT_FORMAT_SFT)
+#define       VI_INPUT_YUV_INPUT_FORMAT_VYUY		BIT(VI_INPUT_YUV_INPUT_FORMAT_SFT)
 #define       VI_INPUT_YUV_INPUT_FORMAT_YUYV		(2 << VI_INPUT_YUV_INPUT_FORMAT_SFT)
 #define       VI_INPUT_YUV_INPUT_FORMAT_YVYU		(3 << VI_INPUT_YUV_INPUT_FORMAT_SFT)
 #define       VI_INPUT_INPUT_FORMAT_SFT			2  /* bits [5:2] */
@@ -73,7 +73,7 @@
 #define       VI_OUTPUT_H_DIRECTION			BIT(19)
 #define       VI_OUTPUT_YUV_OUTPUT_FORMAT_SFT		17
 #define       VI_OUTPUT_YUV_OUTPUT_FORMAT_UYVY		(0 << VI_OUTPUT_YUV_OUTPUT_FORMAT_SFT)
-#define       VI_OUTPUT_YUV_OUTPUT_FORMAT_VYUY		(1 << VI_OUTPUT_YUV_OUTPUT_FORMAT_SFT)
+#define       VI_OUTPUT_YUV_OUTPUT_FORMAT_VYUY		BIT(VI_OUTPUT_YUV_OUTPUT_FORMAT_SFT)
 #define       VI_OUTPUT_YUV_OUTPUT_FORMAT_YUYV		(2 << VI_OUTPUT_YUV_OUTPUT_FORMAT_SFT)
 #define       VI_OUTPUT_YUV_OUTPUT_FORMAT_YVYU		(3 << VI_OUTPUT_YUV_OUTPUT_FORMAT_SFT)
 #define       VI_OUTPUT_OUTPUT_BYTE_SWAP		BIT(16)
-- 
2.50.0

Re: [PATCH] staging: media: tegra-video: use BIT() macro instead of shift

Posted by Luca Ceresoli 2 months, 1 week ago

Hello A.T. Jefferies,

On Wed, 23 Jul 2025 23:17:57 +0000
"A.T. Jefferies" <alextjefferies@gmail.com> wrote:

> Replace two instances of (1 << X) with BIT(X) in tegra20.c to follow
> kernel coding style guidelines and improve clarity. The BIT() macro
> also ensures proper type handling for larger shifts.
> 
> Signed-off-by: A.T. Jefferies <alextjefferies@gmail.com>
> ---
>  drivers/staging/media/tegra-video/tegra20.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/media/tegra-video/tegra20.c b/drivers/staging/media/tegra-video/tegra20.c
> index 7b8f8f810b35..1473f1b1f203 100644
> --- a/drivers/staging/media/tegra-video/tegra20.c
> +++ b/drivers/staging/media/tegra-video/tegra20.c
> @@ -42,7 +42,7 @@
>  #define       VI_INPUT_BT656				BIT(25)
>  #define       VI_INPUT_YUV_INPUT_FORMAT_SFT		8  /* bits [9:8] */
>  #define       VI_INPUT_YUV_INPUT_FORMAT_UYVY		(0 << VI_INPUT_YUV_INPUT_FORMAT_SFT)
> -#define       VI_INPUT_YUV_INPUT_FORMAT_VYUY		(1 << VI_INPUT_YUV_INPUT_FORMAT_SFT)
> +#define       VI_INPUT_YUV_INPUT_FORMAT_VYUY		BIT(VI_INPUT_YUV_INPUT_FORMAT_SFT)
>  #define       VI_INPUT_YUV_INPUT_FORMAT_YUYV		(2 << VI_INPUT_YUV_INPUT_FORMAT_SFT)
>  #define       VI_INPUT_YUV_INPUT_FORMAT_YVYU		(3 << VI_INPUT_YUV_INPUT_FORMAT_SFT)

Thanks for your patch. However I'm afraid I don't think this is a good
idea. 1 is just one out of 4 possible values out of 4 possible values
for a multi-bit register field. All the 4 should use the same style.

BIT() is perfect for single-bit register fields. It's not for multi-bit
fields.

Luca

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