Subject: [PATCH-next] media: s2255drv: Remove unneeded if else blocks

Given the following definitions from s2255drv.c

#define LINE_SZ_4CIFS_NTSC 640
#define LINE_SZ_2CIFS_NTSC 640
#define LINE_SZ_1CIFS_NTSC 320

and

#define LINE_SZ_4CIFS_PAL 704
#define LINE_SZ_2CIFS_PAL 704
#define LINE_SZ_1CIFS_PAL 352

f->fmt.pix.width possible values can be reduced to
LINE_SZ_4CIFS_NTSC or LINE_SZ_1CIFS_NTSC.

This patch removes unneeded if else blocks in vidioc_try_fmt_vid_cap
function.

This issue was detected by using the Coccinelle software.

Signed-off-by: Christopher Díaz Riveros <[email protected]>
---
drivers/media/usb/s2255/s2255drv.c | 8 --------
1 file changed, 8 deletions(-)

diff --git a/drivers/media/usb/s2255/s2255drv.c b/drivers/media/usb/s2255/s2255drv.c
index 8c2a86d71e8a..a00a15f55d37 100644
--- a/drivers/media/usb/s2255/s2255drv.c
+++ b/drivers/media/usb/s2255/s2255drv.c
@@ -803,10 +803,6 @@ static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
}
if (f->fmt.pix.width >= LINE_SZ_4CIFS_NTSC)
f->fmt.pix.width = LINE_SZ_4CIFS_NTSC;
- else if (f->fmt.pix.width >= LINE_SZ_2CIFS_NTSC)
- f->fmt.pix.width = LINE_SZ_2CIFS_NTSC;
- else if (f->fmt.pix.width >= LINE_SZ_1CIFS_NTSC)
- f->fmt.pix.width = LINE_SZ_1CIFS_NTSC;
else
f->fmt.pix.width = LINE_SZ_1CIFS_NTSC;
} else {
@@ -820,10 +816,6 @@ static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
}
if (f->fmt.pix.width >= LINE_SZ_4CIFS_PAL)
f->fmt.pix.width = LINE_SZ_4CIFS_PAL;
- else if (f->fmt.pix.width >= LINE_SZ_2CIFS_PAL)
- f->fmt.pix.width = LINE_SZ_2CIFS_PAL;
- else if (f->fmt.pix.width >= LINE_SZ_1CIFS_PAL)
- f->fmt.pix.width = LINE_SZ_1CIFS_PAL;
else
f->fmt.pix.width = LINE_SZ_1CIFS_PAL;
}
--
2.16.0



2018-01-25 08:46:59

by walter harms

[permalink] [raw]
Subject: Re: [PATCH-next] media: s2255drv: Remove unneeded if else blocks



Am 24.01.2018 22:40, schrieb Christopher Díaz Riveros:
> Given the following definitions from s2255drv.c
>
> #define LINE_SZ_4CIFS_NTSC 640
> #define LINE_SZ_2CIFS_NTSC 640
> #define LINE_SZ_1CIFS_NTSC 320
>
> and
>
> #define LINE_SZ_4CIFS_PAL 704
> #define LINE_SZ_2CIFS_PAL 704
> #define LINE_SZ_1CIFS_PAL 352
>
> f->fmt.pix.width possible values can be reduced to
> LINE_SZ_4CIFS_NTSC or LINE_SZ_1CIFS_NTSC.
>
> This patch removes unneeded if else blocks in vidioc_try_fmt_vid_cap
> function.
>
> This issue was detected by using the Coccinelle software.
>
> Signed-off-by: Christopher Díaz Riveros <[email protected]>

mmmh, yes and no.
i guess the author tries to document the change from 4->2->1

The whole thing gets more obvoius when you use hex and look at the bits:
704 = 0x2C0 = 001011000000
640 = 0x280 = 001010000000
352 = 0x160 = 000101100000
320 = 0x140 = 000101000000

so they only flip one bit and shift the mask. perhaps you can use that
to simplify the code ?

re
wh
> ---
> drivers/media/usb/s2255/s2255drv.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/drivers/media/usb/s2255/s2255drv.c b/drivers/media/usb/s2255/s2255drv.c
> index 8c2a86d71e8a..a00a15f55d37 100644
> --- a/drivers/media/usb/s2255/s2255drv.c
> +++ b/drivers/media/usb/s2255/s2255drv.c
> @@ -803,10 +803,6 @@ static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
> }
> if (f->fmt.pix.width >= LINE_SZ_4CIFS_NTSC)
> f->fmt.pix.width = LINE_SZ_4CIFS_NTSC;
> - else if (f->fmt.pix.width >= LINE_SZ_2CIFS_NTSC)
> - f->fmt.pix.width = LINE_SZ_2CIFS_NTSC;
> - else if (f->fmt.pix.width >= LINE_SZ_1CIFS_NTSC)
> - f->fmt.pix.width = LINE_SZ_1CIFS_NTSC;
> else
> f->fmt.pix.width = LINE_SZ_1CIFS_NTSC;
> } else {
> @@ -820,10 +816,6 @@ static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
> }
> if (f->fmt.pix.width >= LINE_SZ_4CIFS_PAL)
> f->fmt.pix.width = LINE_SZ_4CIFS_PAL;
> - else if (f->fmt.pix.width >= LINE_SZ_2CIFS_PAL)
> - f->fmt.pix.width = LINE_SZ_2CIFS_PAL;
> - else if (f->fmt.pix.width >= LINE_SZ_1CIFS_PAL)
> - f->fmt.pix.width = LINE_SZ_1CIFS_PAL;
> else
> f->fmt.pix.width = LINE_SZ_1CIFS_PAL;
> }