Re: [PATCH 2/6] arm64: dts: qcom: sm8550-qrd: remove data-lanes property of image sensor

[Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>]

On 12/3/25 13:50, Konrad Dybcio wrote:
> On 12/3/25 12:41 PM, Vladimir Zapolskiy wrote:
>> On 12/3/25 13:11, Konrad Dybcio wrote:
>>> On 12/3/25 5:05 AM, Vladimir Zapolskiy wrote:
>>>> Samsung S5K3M5 image sensor supports only 4-lane MIPI CSI-2 interface,
>>>> which makes the sensor data-lanes property redundant, and it can be
>>>> safely removed from the board dts file. Noteworthy that the property
>>>> value is incorrect, because conventionally lanes enumeration of image
>>>> sensors starts from index 1.
>>>
>>> This seems to vary between sensors
>>>
>>
>> It should not, from Documentation/devicetree/bindings/media/video-interfaces.yaml
>> the clock lane has index 0, data lanes enumeration starts from 1:
>>
>>    data-lanes:
>>    ....
>>      description:
>>        An array of physical data lane indexes. Position of an entry determines
>>        the logical lane number, while the value of an entry indicates physical
>>        lane, e.g. for 2-lane MIPI CSI-2 bus we could have "data-lanes = <1 2>;",
>>        assuming the clock lane is on hardware lane 0.
> 
> I interpret the last sentence as ">>if<< the clock lane is 0, then data lanes
> start at 1. I'm not sure if the spec mandates that's the case though.
> 

Well, that's the absolute common practice for media devices, which I'd like
to follow without a deviation from it or introducing a novation.

The dt bindings documentation of this S5K3M5 sensor device describes the value
of the optional data-lanes property accordingly:

https://lore.kernel.org/linux-media/20251203040241.71018-2-vladimir.zapolskiy@linaro.org/

So, I belive, this change under review should be fine as is.

-- 
Best wishes,
Vladimir