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

Kuan-Wei Chiu
2025-04-09T18:31:02Z

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@gmail.com>
> > Signed-off-by: Yu-Chun Lin <eleanor15x@gmail.com>
> > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.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@gmail.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)