linux-kernel - [PATCH 1/2] dt-bindings: hwmon: pwm-fan: Document default-pwm property

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Message-Id: <20250102175041.822977-1-peter@korsgaard.com>
Date: Thu,  2 Jan 2025 18:50:40 +0100
From: Peter Korsgaard <peter@...sgaard.com>
To: Guenter Roeck <linux@...ck-us.net>,
	devicetree@...r.kernel.org,
	linux-hwmon@...r.kernel.org
Cc: Peter Korsgaard <peter@...sgaard.com>,
	Jean Delvare <jdelvare@...e.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/2] dt-bindings: hwmon: pwm-fan: Document default-pwm property

The pwm-fan driver uses full PWM (255) duty cycle at startup, which may not
always be desirable because of noise or power consumption peaks, so add an
optional "default-pwm" property that can be used to specify a custom default
PWM duty cycle.

Signed-off-by: Peter Korsgaard <peter@...sgaard.com>
---
 Documentation/devicetree/bindings/hwmon/pwm-fan.yaml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/hwmon/pwm-fan.yaml b/Documentation/devicetree/bindings/hwmon/pwm-fan.yaml
index 8b4ed5ee962f..83b8b0b964ee 100644
--- a/Documentation/devicetree/bindings/hwmon/pwm-fan.yaml
+++ b/Documentation/devicetree/bindings/hwmon/pwm-fan.yaml
@@ -20,6 +20,12 @@ properties:
     items:
       maximum: 255
 
+  default-pwm:
+    description: Default PWM duty cycle value to use at startup
+    minimum: 0
+    maximum: 255
+    default: 255
+
   fan-supply:
     description: Phandle to the regulator that provides power to the fan.
 
@@ -100,6 +106,7 @@ examples:
     pwm-fan {
       compatible = "pwm-fan";
       pwms = <&pwm 0 40000 0>;
+      default-pwm = 75;
       fan-supply = <&reg_fan>;
       interrupt-parent = <&gpio5>;
       interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
-- 
2.39.5