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

[Krzysztof Kozlowski <krzk@kernel.org>]

On 10/04/2026 05:04, Hongliang Wang wrote:
> Hi, Krzysztof
> 
> On 2026/4/9 下午8:11, Krzysztof Kozlowski wrote:
>> On 09/04/2026 14:03, Hongliang Wang wrote:
>>> 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,
>>> 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.
>>>
>> You should determine/calculate the divisor in the driver code, depending
>> on clocks and bus frequencies. You don't need a property for that, usually.
> 
> Not only clocks and bus frequencies, but also a third property is required.
> 
> The frequency divison calculation formula of i2c is
> Prcescale = clock_a/(clock_div*clock_s)-1
> 
> There is three parameters in this formula:
> clock_a represents the input clock, which is described by "clocks",
> clock_s represents the i2c bus frequency, which is described by 
> "clock-frequency",
> but there is no existing property to describe clock_div, which has 
> different value
> on different platform (for example, it is 5 on 7a1000/7a2000, 4 on 
> 2K1000/2K2000,
> 5.5 on 2K3000.), So I need a property to describe clock_div in this formula.

So it is fixed per compatible? Then you do not need.


Best regards,
Krzysztof