netdev - Re: [PATCH v4 05/13] serial: max3100: Replace open-coded parity calculation with parity

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Message-ID: <Z/a82sdjEDaqE9v0@visitorckw-System-Product-Name>
Date: Thu, 10 Apr 2025 02:30:50 +0800
From: Kuan-Wei Chiu <visitorckw@...il.com>
To: Yury Norov <yury.norov@...il.com>
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	Yu-Chun Lin <eleanor15x@...il.com>
Subject: Re: [PATCH v4 05/13] serial: max3100: Replace open-coded parity
 calculation with parity_odd()

On Wed, Apr 09, 2025 at 01:24:08PM -0400, Yury Norov wrote:
> On Wed, Apr 09, 2025 at 11:43:48PM +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/tty/serial/max3100.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
> > index f2dd83692b2c..36ed41eef7b1 100644
> > --- a/drivers/tty/serial/max3100.c
> > +++ b/drivers/tty/serial/max3100.c
> > @@ -16,6 +16,7 @@
> >  /* 4 MAX3100s should be enough for everyone */
> >  #define MAX_MAX3100 4
> >  
> > +#include <linux/bitops.h>
> >  #include <linux/container_of.h>
> >  #include <linux/delay.h>
> >  #include <linux/device.h>
> > @@ -133,7 +134,7 @@ static int max3100_do_parity(struct max3100_port *s, u16 c)
> >  	else
> >  		c &= 0xff;
> >  
> > -	parity = parity ^ (hweight8(c) & 1);
> > +	parity = parity ^ parity_odd(c);
> 
> This can be simplified for more unless I misunderstand something...
> 
I usually don't change the existing coding style since each subsystem
may have its own preferred style.  

But yeah, if this is the preferred way, I can make this change in the
next version.

Regards,
Kuan-Wei

> From: Yury Norov <yury.norov@...il.com>
> Date:   Wed Apr 9 13:22:04 2025 -0400
> 
> serial: max3100: Replace open-coded parity
> 
> diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
> index f2dd83692b2c..07d332b8e87d 100644
> --- a/drivers/tty/serial/max3100.c
> +++ b/drivers/tty/serial/max3100.c
> @@ -121,20 +121,12 @@ static DEFINE_MUTEX(max3100s_lock);		   /* race on probe */
>  
>  static int max3100_do_parity(struct max3100_port *s, u16 c)
>  {
> -	int parity;
> -
> -	if (s->parity & MAX3100_PARITY_ODD)
> -		parity = 1;
> -	else
> -		parity = 0;
> -
>  	if (s->parity & MAX3100_7BIT)
>  		c &= 0x7f;
>  	else
>  		c &= 0xff;
>  
> -	parity = parity ^ (hweight8(c) & 1);
> -	return parity;
> +	return s->parity & MAX3100_PARITY_ODD ? !parity(c) : parity(c);
>  }
>  
>  static int max3100_check_parity(struct max3100_port *s, u16 c)