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

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Message-ID: <lr77avehdf3skwd5o2yur4hvbxhyx2spzve3wpo733l74ppjcx@mn34escjt542>
Date: Thu, 23 Oct 2025 12:34:23 +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 Troy,

On Wed, Oct 22, 2025 at 09:48:04AM +0800, Troy Mitchell wrote:
> On Tue, Oct 21, 2025 at 06:03:34PM +0200, Andi Shyti wrote:
> > On Mon, Oct 20, 2025 at 11:28:45AM +0200, Andi Shyti wrote:
> > > 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>
> > > 
> > > merged to i2c/i2c-host.
> > 
> > I'm sorry, because of the report from LKP(*) I reverted your
> > patch. I2C_K1 is selected by MFD_SPACEMIT_P1, so that we get the
> > following warning:
> > 
> >   WARNING: unmet direct dependencies detected for I2C_K1
> > 
> > and compile I2C_K1 without COMMON_CLK. Please, fix it and
> > resubmit the patch.
> Yes, I noticed that too. The issue is introduced by PMIC driver(P1)
> instead of I2C.
> Should I resubmit this patch right after sending the fix,
> or wait until the fix gets merged first?

I have reverted the patch. Please send them both in the same
series, where the first patch is the "fix" (or preparation to
this patch) and then this patch.

Thanks,
Andi