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From: "Troy Mitchell" <troy.mitchell@linux.spacemit.com>
To: "Stephen Boyd" <sboyd@kernel.org>,
	"Brian Masney" <bmasney+clk@redhat.com>,
	"Jerome Brunet" <jbrunet+clk@baylibre.com>,
	"Yixun Lan" <dlan@kernel.org>, "Alex Elder" <elder@riscstar.com>,
	"Inochi Amaoto" <inochiama@outlook.com>,
	"Haylen Chu" <heylenay@4d2.org>
Cc: <linux-clk@vger.kernel.org>, <linux-riscv@lists.infradead.org>,
	<spacemit@lists.linux.dev>, <linux-kernel@vger.kernel.org>,
	"Troy Mitchell" <troy.mitchell@linux.spacemit.com>,
	"Yao Zi" <me@ziyao.cc>
Subject: Re: [PATCH 2/5] clk: spacemit: make MIX rate selection consistent
Date: Thu, 10 Sep 2026 22:19:54 +0800	[thread overview]
Message-ID: <DLBPALH9J84H.6CTB8GOVYSZ@linux.spacemit.com> (raw)
In-Reply-To: <aqKqKkXbTkcS-pnY@pie>


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On Thu, Sep 10, 2026 at 01:01:30PM +0000, Yao Zi wrote:
> [...]
>
> > @@ -107,22 +107,27 @@ ccu_mix_calc_best_rate(struct clk_hw *hw, unsigned long rate,
> >  	struct ccu_mix *mix = hw_to_ccu_mix(hw);
> >  	unsigned int parent_num = clk_hw_get_num_parents(hw);
> >  	struct ccu_div_config *div = &mix->div;
> > -	u32 div_max = 1 << div->width;
> >  	unsigned long best_rate = 0;
> > +	unsigned long best_delta = ULONG_MAX;
> >  
> >  	for (int i = 0; i < parent_num; i++) {
> >  		struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
> >  		unsigned long parent_rate;
> > +		u32 div_max = 1 << div->width;
>
> div_max should be invariant across iterations. Is there a reason moving
> it inside the loop?

It is invariant in this patch. Moving the declaration was preparation
for patch 3, which makes the limit depend on the parent being considered:

    u32 div_max = div->bypass & BIT(i) ? 1 : 1 << div->width;

K3 bypasses the divider for some parents, so those parents must only be
considered with a divisor of one.

I will keep the declaration outside the loop in patch 2 and move it
inside when introducing the bypass handling in patch 3. This does not
change the final code.

                                            - Troy

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  reply	other threads:[~2026-09-10 14:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-09 14:07 [PATCH 0/5] clk: spacemit: preserve and safely synchronize firmware PLLs Troy Mitchell
2026-09-09 14:07 ` [PATCH 1/5] clk: spacemit: derive PLL rates from hardware Troy Mitchell
2026-09-09 14:07 ` [PATCH 2/5] clk: spacemit: make MIX rate selection consistent Troy Mitchell
2026-09-10 13:01   ` Yao Zi
2026-09-10 14:19     ` Troy Mitchell [this message]
2026-09-09 14:07 ` [PATCH 3/5] clk: spacemit: describe CPU clock dividers and shared PLL muxes Troy Mitchell
2026-09-09 14:07 ` [PATCH 4/5] clk: spacemit: reject rate changes to running firmware PLLs Troy Mitchell
2026-09-10 13:31   ` Yao Zi
2026-09-11  2:02     ` Troy Mitchell
2026-09-11  6:08       ` Yao Zi
2026-09-09 14:07 ` [PATCH 5/5] clk: spacemit: safely synchronize PLL parameters during init Troy Mitchell

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