[PATCH 2/3] dt-bindings: usb: mtk-xhci: Allow middle optional clocks to be missing

["Nícolas F. R. A. Prado" <nfraprado@collabora.com>]

The current clock list in the binding doesn't allow for one of the
optional clocks to be missing and a subsequent clock to be present. An
example where this is an issue is in mt8192.dtsi, which has "sys_ck",
"ref_ck", "xhci_ck" and would cause dtbs_check warnings.

Change the clock list in a way that allows the middle optional clocks to
be missing, while still guaranteeing a fixed order. The "ref_ck" is kept
as a const even though it is optional for simplicity, since it is
present in all current dts files.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
---

 .../devicetree/bindings/usb/mediatek,mtk-xhci.yaml       | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
index 63cbc2b62d18..99a1b233ec90 100644
--- a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
+++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
@@ -80,8 +80,13 @@ properties:
     items:
       - const: sys_ck  # required, the following ones are optional
       - const: ref_ck
-      - const: mcu_ck
-      - const: dma_ck
+      - enum:
+          - mcu_ck
+          - dma_ck
+          - xhci_ck
+      - enum:
+          - dma_ck
+          - xhci_ck
       - const: xhci_ck
 
   assigned-clocks:
-- 
2.36.1