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

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Message-ID: <20251019232455-GYB1506524@gentoo.org>
Date: Mon, 20 Oct 2025 07:24:55 +0800
From: Yixun Lan <dlan@...too.org>
To: Andi Shyti <andi.shyti@...nel.org>
Cc: Troy Mitchell <troy.mitchell@...ux.spacemit.com>,
	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 Andi,

On 00:32 Mon 20 Oct     , Andi Shyti wrote:
> 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?
> 
Please go ahead, I gave a Reviewed-by, thanks

-- 
Yixun Lan (dlan)