In USB Type-C altmode hot plug interrupts are transferred using sideband
channels. Introduce an additional port in the usb-c-connector to allow
referencing the recipient of these notifications.
A typical node to be referred is a DisplayPort controller.
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
---
I have a USB Type-C port manager with two usb-c-connector child nodes and I
have two display-port controller nodes. I need a way to link each port with
it's related displayport controller, for the purpose of passing hot-plug events
from USB PD to the dp driver.
The displayport binding [1] specifies port@1 as "Output endpoint of the
controller" and in case of being connected to an eDP panel or a dp-controller
this links the node with whatever the output is.
It has been suggested by some to describe the link from the usb-c-connector add
a displayport = <&phandle> to each usb-c-connector node, but the proposed
solution here would make the usb-c-connector case follow the same scheme as
these other cases.
Also, using the graph would allow an implementation of either the tcpm just
notifying the referenced displayport-controller, or following the dp-controller
implementation in Linux implement a drm_bridge and use the reference in the
other direction.
To clarify the end result would look something like:
tcpm {
connector@0 {
compatible = "usb-c-connector";
reg = <0>;
ports {
port@0 {
reg = <0>;
endpoint {
remote-endpoint = <&usb0_hs_mux>;
};
};
port@1 {
reg = <1>;
endpoint {
remote-endpoint = <&usb0_ss_mux>;
};
};
port@2 {
reg = <2>;
endpoint {
remote-endpoint = <&usb0_sbu_switch>;
};
};
connector0_dp0: port@3 {
reg = <1>;
endpoint {
remote-endpoint = <&dp0_connector0>;
};
};
};
};
connector@1 {
compatible = "usb-c-connector";
reg = <1>;
ports {
port@0 {
reg = <0>;
endpoint {
remote-endpoint = <&usb1_hs_mux>;
};
};
port@1 {
reg = <1>;
endpoint {
remote-endpoint = <&usb1_ss_mux>;
};
};
port@2 {
reg = <2>;
endpoint {
remote-endpoint = <&usb1_sbu_switch>;
};
};
connector1_dp1: port@3 {
reg = <1>;
endpoint {
remote-endpoint = <&dp1_connector1>;
};
};
};
};
}
displayport-controller@0 {
reg = <0x0>;
ports {
port@1 {
reg = <1>;
dp0_connector0: endpoint {
remote-endpoint = <&connector0_dp0>;
};
};
};
};
displayport-controller@1 {
reg = <0x1>;
ports {
port@1 {
reg = <1>;
dp1_connector1: endpoint {
remote-endpoint = <&connector1_dp1>;
};
};
};
};
[1] https://www.kernel.org/doc/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
.../devicetree/bindings/connector/usb-connector.yaml | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/Documentation/devicetree/bindings/connector/usb-connector.yaml b/Documentation/devicetree/bindings/connector/usb-connector.yaml
index 0420fa563532..99d4aeb233e5 100644
--- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
+++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
@@ -189,6 +189,12 @@ properties:
description: Sideband Use (SBU), present in USB-C. This describes the
alternate mode connection of which SBU is a part.
+ port@3:
+ $ref: /schemas/graph.yaml#/properties/port
+ description: Out-of-band notifications. This describes the logical
+ connection to e.g. a DisplayPort controller that should be notified
+ about hot plug events.
+
required:
- port@0
--
2.35.1
