Re: [RFC PATCH 0/3] media: qcom: camss: support for empty endpoint nodes

[Richard Acayan <mailingradian@gmail.com>]

On Tue, Dec 30, 2025 at 10:18:39AM +0200, Vladimir Zapolskiy wrote:
> On 12/30/25 04:27, Richard Acayan wrote:
> > This series adds support for empty endpoint nodes. It is currently RFC
> > because it continues an ongoing discussion on how to selectively connect
> > some CAMSS ports to cameras and leave others disconnected.
> > 
> > The SDM670 patches are for a full example. If agreed on, this should
> > expand to SoCs that have CAMSS.
> > 
> > Example SoC dtsi:
> > 
> > 	camss: isp@00000000 {
> > 		...
> > 
> > 		status = "disabled";
> > 
> > 		ports {
> > 			#address-cells = <1>;
> > 			#size-cells = <0>;
> > 
> > 			port@0 {
> > 				reg = <0>;
> > 
> > 				camss_endpoint0: endpoint {
> > 				};
> > 			};
> 
> I do not see this device tree node layout as a valid one. A 'port' provides
> an interface description (an option), and an 'endpoint' declares a connection
> over a port (the accepted option).
> 
> From dtschema/schemas/graph.yaml:
> 
>     Each port node contains an 'endpoint' subnode for each remote device port
>     connected to this port.
> 
> This is violated in the example given by you above, when a remote device along
> with its ports is just missing, thus there is no connection. A forced alternative
> reading may (or will) break the legacy, so in this particular case you shall
> start from making a change to the shared graph.yaml documentation, since it's
> all not about CAMSS or even linux-media specifics.

So, if endpoints MUST/SHALL (in IETF RFC 2119 terms) have a remote, then
would it be acceptable to label the ports instead, so a board DTS can
specify its own fully connected endpoint(s) under the port labels?

The labels to ports aren't looking as "excessive"[1] as they used to be.
Is the original review comment on port labels still relevant?

[1] https://lore.kernel.org/r/565d14e1-1478-4a60-8f70-a76a732cde97@linaro.org