linux-kernel - Re: [PATCH] clk: sunxi-ng: mp: Avoid computing the rate twice

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Date:   Sat, 31 Dec 2022 11:21:43 -0600
From:   Samuel Holland <samuel@...lland.org>
To:     Stephen Boyd <sboyd@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH] clk: sunxi-ng: mp: Avoid computing the rate twice

Hi Stephen,

On 8/15/22 12:26, Stephen Boyd wrote:
> Quoting Samuel Holland (2022-08-09 18:40:24)
>> ccu_mp_find_best() already computes a best_rate at the same time as the
>> best m and p factors. Return it so the caller does not need to duplicate
>> the division.
> 
> Did the compiler figure this out and thus this patch makes no difference
> to the final object code?

It makes a difference at least on my gcc version 11.1.0.

Before:
   text    data     bss     dec     hex filename
  18257      12       0   18269    475d drivers/clk/sunxi-ng/sunxi-ccu.o

After:
   text    data     bss     dec     hex filename
  18083      12       0   18095    46af drivers/clk/sunxi-ng/sunxi-ccu.o

I will send a v2 covering all of the CCU clock types.

Regards,
Samuel