Re: [PATCH 2/3] dt-bindings: media: i2c: Add vision-components,mipi-module-controller

[Krzysztof Kozlowski <krzk@kernel.org>]

On 17/09/2026 09:55, Richard Leitner wrote:
>> There is no "clocks" property in the binding. If there is input, then
>> there is a "clocks".
>>
>> Then we never describe external oscillators with "clock-frequency"
>> property. ACPI does, but not DT.
> 
> So how would that be best solved in DT?
> 
> Should there be a "fixed-clock" child node for that external oscillator?
> Something like:
> 
> vc_mipi_ctrl: controller@10 {
>   ...
> 
>   vc_mipi_clk: clock {
>     compatible = "fixed-clock";
>     #clock-cells = <0>;
>     clock-frequency = <37125000>;
>   };
> 

Oh, wait, I misread. The external oscillator is not external to the
module? Below...


>   i2c-tunnel {
>     ...
> 
>     vc_mipi_sensor: camera@60 {
>       ...
> 
>       clocks = <&vc_mipi_clk>;
>       clock-names = "inck";
>     };
> };
> 
> Or should (as discussed in the other branch of this thread) there be a
> separate compatible for every vc-mipi sensor variant board? Then this
> could also be part of the compatible-dependent driver data.
> 
> Or are there any other/better approaches to this?
> 
>>
>>
>>> uses it for internal purpose, and also to provide a clock to the sensor.
>>> Very roughly speaking, and ignoring power supplies as we focus on the
>>> clocks, the camera module is architectured this way:
>>>
>>> Connector
>>>    ||                                       +--------+
>>>    || <------------ MIPI CSI-2 ------------ |        |
>>>    ||               +-------+               |        |
>>>    || <--- I2C ---> |       | <--- I2C ---> | Sensor |
>>>    ||               | FPGA  |               |        |
>>>    ||               |       | --- Clock --> |        |
>>>    ||               +-------+               +--------+
>>>                         ^
>>>                         |
>>>                     +-------+
>>>                     | Clock |
>>>                     | Osc.  |
>>>                     +-------+
>>>
>>> The frequency of the external clock oscillator is what the
>>> clock-frequency models.
>>>


... this sentence confused me. If the oscillator is part of the module,
then clock-frequency property is applicable or it is implied by the
compatible.


Best regards,
Krzysztof