Re: [PATCH 2/2] phy: qcom-mipi-csi2: Add a CSI2 MIPI D-PHY driver

[Bryan O'Donoghue]

On 21/07/2025 16:46, neil.armstrong@xxxxxxxxxx wrote:
> On 15/07/2025 11:33, Konrad Dybcio wrote:
> > On 7/15/25 11:20 AM, Vladimir Zapolskiy wrote:
> > > On 7/15/25 12:01, Konrad Dybcio wrote:
> > > > On 7/15/25 8:35 AM, Vladimir Zapolskiy wrote:
> > > > > On 7/15/25 03:13, Bryan O'Donoghue wrote:
> > > > > > On 14/07/2025 16:30, Vladimir Zapolskiy wrote:
> > > > > > > > I think that is genuinely something we should handle in camss-csid.c
> > > > > > > > maybe with some meta-data inside of the ports/endpoints..
> > > > > > >
> > > > > > > This is a CSIPHY property, a CSIPHY hardware configuration and a wiring
> > > > > > > of sensors to a CSIPHY. Where is the relation to CSID here? There is no.
> > > > > >
> > > > > > All the PHY really needs to know is the # of lanes in aggregate, which
> > > > > > physical lanes to map to which logical lanes and the pixel clock.
> > > > > >
> > > > > > We should add additional support to the Kernel's D-PHY API parameters
> > > > > > mechanism to support that physical-to-logical mapping but, that's not
> > > > > > required for this series or for any currently know upstream user of CAMSS.
> > > > > >
> > > > > > > Please share at least a device tree node description, which supports
> > > > > > > a connection of two sensors to a single CSIPHY, like it shall be done
> > > > > > > expectedly.
> > > > > > &camss {
> > > > > >          port@0 {
> > > > > >              csiphy0_lanes01_ep: endpoint0 {
> > > > > >                  data-lanes = <0 1>;
> > > > > >                  remote-endpoint = <&sensor0_ep>;
> > > > > >              };
> > > > > >
> > > > > >              csiphy0_lanes23_ep: endpoint0 {
> > > > > >                  data-lanes = <2 3>;
> > > > > >                  remote-endpoint = <&sensor1_ep>;
> > > > > >              };
> > > > > >           };
> > > > > > };
> > > > >
> > > > > Don't you understand that this is broken?.. That's no good.
> > > > >
> > > > > Please listen and reread the messages given to you above, your proposed
> > > > > "solution" does not support by design a valid hardware setup of two
> > > > > sensors connected to the same CSIPHY.
> > > > >
> > > > > I would propose to stop force pushing an uncorrectable dt scheme, it
> > > > > makes no sense.
> > > >
> > > > If all you're asking for is an ability to grab an of_graph reference
> > > > from the camss (v4l2) driver, you can simply do something along the
> > > > lines of of_graph_get_remote_port(phy->dev->of_node)
> > >
> > > It's not about the driver specifics, my comment is about a proper
> > > hardware description in dts notation, please see the device tree node
> > > names.
> >
> > I'm a little lost on what you're trying to argue for..
> >
> > I could make out:
> >
> > 1. "the phy should be a multimedia device"
> > 2. "There is no ports at all, which makes the device tree node unusable,
> >     since you can not provide a way to connect any sensors to the phy."
> >
> > I don't really understand #1.. maybe that could be the case if the PHY
> > has a multitude of tunables (which I don't know if it does, but wouldn't
> > be exactly surprised if it did) that may be usecase/pipeline-specific
> >
> > As for #2, I do think it makes sense to connect the sensors to the PHY,
> > as that's a representation of electrical signals travelling from the
> > producer to the consumer (plus the data passed in e.g. data-lanes is
> > directly related to the PHY and necessarily consumed by its driver)
>
> The port/endpoint should represent the data flow, and if the signal is the following:
>
> sensor -> csiphy -> csid

I'll be honest.

I looked at your upstreamed code

drivers/phy/amlogic/phy-meson-axg-mipi-dphy.c 
Documentation/devicetree/bindings/parch/arm64/boot/dts/amlogic/meson-khadas-vim3-ts050.dtsoc/meson-axg.dtsi

And didn't really think CSIPHY needed to be included in the data-graph.

---
bod