Re: [PATCH v5 1/2] dt-bindings: phy: qcom: Add CSI2 C-PHY/DPHY schema

Bryan O'Donoghue
2026-03-27T17:42:21Z

On 27/03/2026 15:28, Neil Armstrong wrote:
>> To be frankly honest you can make an argument for it either way.
>> However my honestly held position is analysing other upstream
>> implementations connecting to the PHY means we can't make the PHY
>> device a drivers/phy device - it would have to be a V4L2 device and
>> then for me the question is why is that even required ?
>
> This is plain wrong, DT definition is different from software
> implementation, you can do whatever you want if you describe HW accurately.

I'm not sure what point it is you are trying to make here. Are you
trying to say drivers/phy is OK with you but you want an endpoint ? If
so, please just say so.

I can see an argument for that hence my response to Konrad, I just don't
see why its a Qualcomm specific argument and of course understood stuff
bubbles up in review, we have a public debate and come to a consensus -
that's a good thing.

However, I'd want wider buy-in and understanding that endpoints in the
PHYs is a more accurate description of the data-flow.

We've been applying DT bindings aplenty without that so far. So we would
establish new CSI2 PHY bindings should represent the sensor endpoints.

Is that what you want ?

> The CSIPHYs are not tied to a single "consumer" block, they can be
> connected to different consumers at runtime, which is not something
> classic PHY devices are designed for. So they are de facto a media
> element in the dynamic camera pipeline.

The existing CAMSS binding and media graph are not changed by this series.

> And actually Rob Herring asked use to define the complete data flow, it
> was a strong requirement. I don't see why we wouldn't here.

I'm implementing feedback from Rob.

https://lore.kernel.org/linux-media/20250710230846.GA44483-robh@kernel.org/

To me, here is where we stand:

- Individual nodes - we all agree that
- As sub-nodes - I think the majority agrees this Krzsztof, Dmitry
I'm fine with it too.
- drivers/phy - I think we are accepting this is also fine ?
- endpoints should flow into the PHY and then back to the controller

I get that argument. In fact I _like_ that argument at least I like my
conception of that argument.

I'll stipulate to that argument meaning then that, new CSI2 PHYs shall
include endpoints for this purpose globally.

As I've said before, there's nothing Qualcomm specific about this
discussion, really.

---
bod