Re: [PATCH v1 1/2] dt-bindings: i2c: ls2x-i2c: Add clock- related properties

[Yao Zi <me@ziyao.cc>]

On Thu, Apr 09, 2026 at 08:03:47PM +0800, Hongliang Wang wrote:
> Hi, Krzysztof
> 
> On 2026/3/31 下午3:11, Hongliang Wang wrote:
> > 
> > On 2026/3/30 下午3:23, Krzysztof Kozlowski wrote:
> > > On 30/03/2026 09:18, Hongliang Wang wrote:
> > > > On 2026/3/27 下午2:39, Krzysztof Kozlowski wrote:
> > > > > On 27/03/2026 04:09, Hongliang Wang wrote:
> > > > > > The initial idea was that this patch could be used for
> > > > > > both ACPI and DTS.
> > > > > > > > > The i2c-ls2x driver is compatible with both Loongson 2K and 3A+7A
> > > > > > > > > platform, parse
> > > > > > > > > the same parameters regardless of dts or
> > > > > > > > > acpi parameter passing, So
> > > > > > > > > clock-input
> > > > > > > > > and clock-div attributes are defined to
> > > > > > > > > describe input clock of i2c
> > > > > > > > > controller and
> > > > > > > > > divisor of input clock. It can be used on
> > > > > > > > > both 2K and 3A+7A platform.
> > > > > > > > And you cannot use them in DTS.
> > > > > > OK
> > > > > > > I need to keep guessing what you want to achieve,
> > > > > > > because neither your
> > > > > > > message nor commit text was explicit
> > > > > > What I want to achieve is to describe the input clock
> > > > > > and divisor of I2C
> > > > > > controller
> > > > > Input clocks are defined as clock inputs obviously in DT, not as
> > > > > integers. Bindings need to describe the hardware, so start with that.
> > > > I can describe the hardware in loongson,ls2x-i2c.yaml, and I
> > > > would like to
> > > > confirm with you what final implementation plan you agree to? clock
> > > > framework
> > > > or custom clock-input an clock-div attributes? if clock framework, how
> > > > can it
> > > > also be used for ACPI?
> > > And you ask DT maintainer for that? It's not relevant. You sent DT
> > > bindings patch, so this patch must be correct and we discuss this patch
> > > here.
> > I don't. My idea is that if the clock input attribute can't be used for
> > both
> > dts and acpi, then clock framework will be used for dts and new define
> > attribute
> > will be used for acpi. I will first implement the hardware description
> > and clock
> > framework in Bindings.
> > > Best regards,
> > > Krzysztof
> > 
> > Best regards,
> > Hongliang Wang
> > 
> 
> I have a question, the input clock of i2c controller can be described by
> "clocks",
> but there is no existing attribute can describe the divisor of the input
> clock,

From the description of 7A1000's user manual (section 2.3
"时钟功能描述"), it seems the divider isn't part of the I2C controller,
but instead is an on-chip divider with fixed 1/2 factor, feeding both
"MISC" block (including I2C) and SPI.

> Can I define a new attribute named "clock-div" to describe it in DT
> bindings?
> or do you have any standard solutions for the divisor problem? Thank you.

If these devicetree-based Loongson platforms follow a similar pattern as
the bridge chip, then the divisor shouldn't be described in the I2C
controller node. You may want to include a "fixed-factor-clock" node to
match the hardware.

> Best regards,
> Hongliang Wang
> 
> 
> 

Regards,
Yao Zi