dt-bindings: usb: cdns,usb3: document USBSSP controller support

Update the Cadence USBSS DRD binding to document that it also covers
the USBSSP (SuperSpeed Plus, USB 3.1 gen2x1) controller. Both USBSS
and USBSSP share the same DRD/OTG register interface, so the driver
auto-detects the controller version at runtime: no additional
compatible string is needed.

Changes to the binding:
- Update title and add description
- maximum-speed: add super-speed-plus

Assisted-by: Cursor:claude-4.6-opus
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Peter Chen <peter.chen@cixtech.com>
Link: https://patch.msgid.link/20260421023459.506145-2-peter.chen@cixtech.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 8 insertions, 2 deletions

diff --git a/Documentation/devicetree/bindings/usb/cdns,usb3.yaml b/Documentation/devicetree/bindings/usb/cdns,usb3.yaml
index a199e5ba6416..2d95fb7321af 100644
--- a/Documentation/devicetree/bindings/usb/cdns,usb3.yaml
+++ b/Documentation/devicetree/bindings/usb/cdns,usb3.yaml
@@ -4,11 +4,17 @@
 $id: http://devicetree.org/schemas/usb/cdns,usb3.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: Cadence USBSS-DRD controller
+title: Cadence USBSS and USBSSP DRD controller
 
 maintainers:
   - Pawel Laszczak <pawell@cadence.com>
 
+description:
+  Cadence USB dual-role controller. Covers USBSS (SuperSpeed, USB 3.0) and
+  USBSSP (SuperSpeed Plus, USB 3.1 gen2x1). Both variants share the same
+  DRD/OTG register interface, so the driver auto-detects the controller
+  version at runtime.
+
 properties:
   compatible:
     const: cdns,usb3
@@ -49,7 +55,7 @@ properties:
       cdns3 to type C connector.
 
   maximum-speed:
-    enum: [super-speed, high-speed, full-speed]
+    enum: [super-speed-plus, super-speed, high-speed, full-speed]
 
   phys:
     minItems: 1