linux-kernel - Re: [PATCH v3 1/4] i2c: spacemit: configure ILCR for accurate SCL frequency

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Message-ID: <4a76e9bf-926e-4b77-a2f8-ee4a72b2f1dd@riscstar.com>
Date: Sun, 28 Dec 2025 18:58:00 -0600
From: Alex Elder <elder@...cstar.com>
To: Troy Mitchell <troy.mitchell@...ux.spacemit.com>,
 Lee Jones <lee@...nel.org>, Yixun Lan <dlan@...too.org>,
 Andi Shyti <andi.shyti@...nel.org>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
 spacemit@...ts.linux.dev, linux-i2c@...r.kernel.org,
 linux-rtc@...r.kernel.org
Subject: Re: [PATCH v3 1/4] i2c: spacemit: configure ILCR for accurate SCL
 frequency

On 12/26/25 1:52 AM, Troy Mitchell wrote:
>>>> +static int spacemit_i2c_clk_set_rate(struct clk_hw *hw, unsigned long rate,
>>>> +				     unsigned long parent_rate)
>>>> +{
>>>> +	struct spacemit_i2c_dev *i2c = container_of(hw, struct spacemit_i2c_dev, scl_clk_hw);
>>>> +	u32 lv, lcr, mask, shift, max_lv;
>>>> +
>>>> +	lv = DIV_ROUND_UP(parent_rate, rate);
>>>
>>> Would DIV_ROUND_CLOSEST() give a more accurate value?
>> I'll test it.
> Same result. So I'll keep it.

Is that true for all clock rates?  Anyway, it's not
a huge deal, but especially when the number of rates
isn't very high this can make a difference.

					-Alex

>                          - Troy