netdev - Re: [PATCH v4 02/13] media: media/test_drivers: Replace open-coded parity calculation with parity

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Message-ID: <Z_aobrK3t7zdwZRK@yury>
Date: Wed, 9 Apr 2025 13:03:42 -0400
From: Yury Norov <yury.norov@...il.com>
To: Kuan-Wei Chiu <visitorckw@...il.com>
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	Yu-Chun Lin <eleanor15x@...il.com>
Subject: Re: [PATCH v4 02/13] media: media/test_drivers: Replace open-coded
 parity calculation with parity_odd()

On Wed, Apr 09, 2025 at 11:43:45PM +0800, Kuan-Wei Chiu wrote:
> Refactor parity calculations to use the standard parity_odd() helper.
> This change eliminates redundant implementations.
> 
> Co-developed-by: Yu-Chun Lin <eleanor15x@...il.com>
> Signed-off-by: Yu-Chun Lin <eleanor15x@...il.com>
> Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>
> ---
>  drivers/media/test-drivers/vivid/vivid-vbi-gen.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/test-drivers/vivid/vivid-vbi-gen.c b/drivers/media/test-drivers/vivid/vivid-vbi-gen.c
> index 70a4024d461e..5e1b7b1742e4 100644
> --- a/drivers/media/test-drivers/vivid/vivid-vbi-gen.c
> +++ b/drivers/media/test-drivers/vivid/vivid-vbi-gen.c
> @@ -5,6 +5,7 @@
>   * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
>   */
>  
> +#include <linux/bitops.h>
>  #include <linux/errno.h>
>  #include <linux/kernel.h>
>  #include <linux/ktime.h>
> @@ -165,12 +166,7 @@ static const u8 vivid_cc_sequence2[30] = {
>  
>  static u8 calc_parity(u8 val)
>  {
> -	unsigned i;
> -	unsigned tot = 0;
> -
> -	for (i = 0; i < 7; i++)
> -		tot += (val & (1 << i)) ? 1 : 0;
> -	return val | ((tot & 1) ? 0 : 0x80);
> +	return val | (parity_odd(val) ? 0 : 0x80);

So, if val == 0 than parity_odd(val) is also 0, and this can be
simplified just to:
        return parity(val) ? 0 : 0x80;
Or I miss something?

>  }
>  
>  static void vivid_vbi_gen_set_time_of_day(u8 *packet)
> -- 
> 2.34.1