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

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Message-ID: <aA3oWzkUP3CYbShi@alpha.franken.de>
Date: Sun, 27 Apr 2025 10:18:35 +0200
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: Thorsten Blum <thorsten.blum@...ux.dev>
Cc: John Crispin <john@...ozen.org>,
	Sergio Paracuellos <sergio.paracuellos@...il.com>,
	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()

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.

Thomas.

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