linux-kernel - [PATCH] dt-bindings: serial: 8250: Make clocks and clock-frequency exclusive

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Message-ID: <20250524105602.53949-1-ziyao@disroot.org>
Date: Sat, 24 May 2025 10:56:02 +0000
From: Yao Zi <ziyao@...root.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Lubomir Rintel <lkundrak@...sk>
Cc: devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org,
	Yao Zi <ziyao@...root.org>
Subject: [PATCH] dt-bindings: serial: 8250: Make clocks and clock-frequency exclusive

The 8250 binding before converting to json-schema states,

  - clock-frequency : the input clock frequency for the UART
  	or
  - clocks phandle to refer to the clk used as per Documentation/devicetree

for clock-related properties, where "or" indicates these properties
shouldn't exist at the same time.

Additionally, the behavior of Linux's driver is strange when both clocks
and clock-frequency are specified: it ignores clocks and obtains the
frequency from clock-frequency, left the specified clocks unclaimed. It
may even be disabled, which is undesired most of the time.

But "anyOf" doesn't prevent these two properties from coexisting, as it
considers the object valid as long as there's at LEAST one match.

Let's switch to "oneOf" and disallows the other property if one exists,
exclusively matching the original binding and avoid future confusion on
the driver's behavior.

Fixes: e69f5dc623f9 ("dt-bindings: serial: Convert 8250 to json-schema")
Signed-off-by: Yao Zi <ziyao@...root.org>
---
 Documentation/devicetree/bindings/serial/8250.yaml | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/serial/8250.yaml b/Documentation/devicetree/bindings/serial/8250.yaml
index dc0d52920575..4322394f5b8f 100644
--- a/Documentation/devicetree/bindings/serial/8250.yaml
+++ b/Documentation/devicetree/bindings/serial/8250.yaml
@@ -45,9 +45,13 @@ allOf:
                   - ns16550
                   - ns16550a
     then:
-      anyOf:
-        - required: [ clock-frequency ]
-        - required: [ clocks ]
+      oneOf:
+        - allOf:
+            - required: [ clock-frequency ]
+            - properties: { clocks: false }
+        - allOf:
+            - required: [ clocks ]
+            - properties: { clock-frequency: false }

 properties:
   compatible:
-- 
2.49.0