linux-kernel - Re: [PATCH v2 2/4] i2c: spacemit: configure ILCR for accurate SCL frequency

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Message-ID: <01C031AEFDAD4CE5+aRQlzq76t3huDaLg@kernel.org>
Date: Wed, 12 Nov 2025 14:14:38 +0800
From: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
To: Lee Jones <lee@...nel.org>, Yixun Lan <dlan@...too.org>,
	Alex Elder <elder@...cstar.com>, 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,
	Troy Mitchell <troy.mitchell@...ux.spacemit.com>
Subject: Re: [PATCH v2 2/4] i2c: spacemit: configure ILCR for accurate SCL
 frequency

On Mon, Oct 27, 2025 at 01:48:06PM +0800, Troy Mitchell wrote:
> The SpacemiT I2C controller's SCL (Serial Clock Line) frequency for
> master mode operations is determined by the ILCR (I2C Load Count Register).
> Previously, the driver relied on the hardware's reset default
> values for this register.
> 
> The hardware's default ILCR values (SLV=0x156, FLV=0x5d) yield SCL
> frequencies lower than intended. For example, with the default
> 31.5 MHz input clock, these default settings result in an SCL
> frequency of approximately 93 kHz (standard mode) when targeting 100 kHz,
> and approximately 338 kHz (fast mode) when targeting 400 kHz.
> These frequencies are below the 100 kHz/400 kHz nominal speeds.
> 
> This patch integrates the SCL frequency management into
> the Common Clock Framework (CCF). Specifically, the ILCR register,
> which acts as a frequency divider for the SCL clock, is now registered
> as a managed clock (scl_clk) within the CCF.
> 
> This patch also cleans up unnecessary whitespace
> in the included header files.
> 
> Reviewed-by: Yixun Lan <dlan@...too.org>
> Signed-off-by: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
> ---
> This patch was affected by the P1 Kconfig, which caused the maintainer
> to revert it.
> The current commit is a direct cherry-pick and reserves the original changelog.
> This note is to clarify for anyone who sees the cover letter marked as v2
> while the changelog entries reach v4.
Hi Andi,
Since the issue affecting the I2C patch has been fixed [1],
I think it should be ready to be merged now. What do you think?

Link: https://lore.kernel.org/all/176244506110.1925720.10807118665958896958.b4-ty@kernel.org/ [1]

                                    - Troy