linux-kernel - Re: [PATCH v4] i2c: spacemit: configure ILCR for accurate SCL frequency

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Message-ID: <b6lafouoz6f6al5ki4oh7jj6gfpejwyh62sdrh7lia37sadd4u@rle3aw6grsiw>
Date: Mon, 20 Oct 2025 00:32:40 +0200
From: Andi Shyti <andi.shyti@...nel.org>
To: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
Cc: Yixun Lan <dlan@...too.org>, linux-i2c@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev
Subject: Re: [PATCH v4] i2c: spacemit: configure ILCR for accurate SCL
 frequency

Hi,

On Fri, Oct 17, 2025 at 03:27:39PM +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.
> 
> Signed-off-by: Troy Mitchell <troy.mitchell@...ux.spacemit.com>

looks OK to me. Yixun, any comment here? Do you mind giving it an
ack?

Andi