linux-kernel - Re: [PATCH] MIPS: ralink: Avoid x/x division in rt_timer

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Message-ID: <CAMhs-H-GYrGMr-yorvYtX1Nud47c5pWrwtcEx9O9kmfJgZiSAw@mail.gmail.com>
Date: Sun, 27 Apr 2025 11:25:41 +0200
From: Sergio Paracuellos <sergio.paracuellos@...il.com>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Thorsten Blum <thorsten.blum@...ux.dev>, John Crispin <john@...ozen.org>, 
	David Laight <david.laight.linux@...il.com>, linux-mips@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: ralink: Avoid x/x division in rt_timer_config()

Hi,

First of all, sorry for missing this patch.

On Sun, Apr 27, 2025 at 10:19 AM Thomas Bogendoerfer
<tsbogend@...ha.franken.de> wrote:
>
> On Tue, Apr 08, 2025 at 10:28:05AM +0200, Thorsten Blum wrote:
> > Avoid the 'rt->timer_freq / rt->timer_freq' division when the divisor is
> > larger than the timer frequency and use '1' directly.
> >
> > No functional changes intended.
> >
> > Suggested-by: David Laight <david.laight.linux@...il.com>
> > Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
> > ---
> >  arch/mips/ralink/timer.c | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/mips/ralink/timer.c b/arch/mips/ralink/timer.c
> > index 54094f6e033e..5d8286603584 100644
> > --- a/arch/mips/ralink/timer.c
> > +++ b/arch/mips/ralink/timer.c
> > @@ -75,12 +75,16 @@ static int rt_timer_request(struct rt_timer *rt)
> >
> >  static int rt_timer_config(struct rt_timer *rt, unsigned long divisor)
> >  {
> > -     if (rt->timer_freq < divisor)
> > +     u32 t;
> > +
> > +     if (rt->timer_freq < divisor) {
> >               rt->timer_div = rt->timer_freq;
> > -     else
> > +             t = 1;
> > +     } else {
> >               rt->timer_div = divisor;
> > -
> > -     rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
> > +             t = rt->timer_freq / rt->timer_div;
> > +     }
> > +     rt_timer_w32(rt, TIMER_REG_TMR0LOAD, t);
>
> I really don't see the point for this change. IMHO, this isn't really
> runtime critical and I prefer the code like it is at the moment.

Yes, I agree with you. I also prefer the code as it is.

Thanks,
    Sergio Paracuellos

>
> Thomas.
>
> --
> Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
> good idea.                                                [ RFC1925, 2.3 ]