[PATCH v3 1/2] dt-bindings: usb: cdns,usb3: document USBSSP controller support

[Peter Chen <peter.chen@cixtech.com>]

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>
---
 Documentation/devicetree/bindings/usb/cdns,usb3.yaml | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/usb/cdns,usb3.yaml b/Documentation/devicetree/bindings/usb/cdns,usb3.yaml
index f454ddd9bbaa..ad5acf956edf 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
-- 
2.50.1