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80bc64201e
Delta AFC0612DB-F00 fan has to be set to at least 30% PWM duty cycle to spin up from a stopped state, and can be afterward throttled down to lower PWM duty cycle. Introduce support for operating such fans which need to start at higher PWM duty cycle first and can slow down next. Document two new DT properties, "fan-stop-to-start-percent" and "fan-stop-to-start-usec". The former describes the minimum percent of fan RPM at which it will surely spin up from stopped state. This value can be found in the fan datasheet and can be converted to PWM duty cycle easily. The "fan-stop-to-start-usec" describes the minimum time in microseconds for which the fan has to be set to stopped state start RPM for the fan to surely spin up. Signed-off-by: Marek Vasut <marex@denx.de> Acked-by: Conor Dooley <conor.dooley@microchip.com> Message-ID: <20241106185925.223736-1-marex@denx.de> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
107 lines
2.5 KiB
YAML
107 lines
2.5 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/hwmon/pwm-fan.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: Fan connected to PWM lines
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maintainers:
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- Jean Delvare <jdelvare@suse.com>
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- Guenter Roeck <linux@roeck-us.net>
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properties:
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compatible:
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const: pwm-fan
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cooling-levels:
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description: PWM duty cycle values corresponding to thermal cooling states.
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$ref: /schemas/types.yaml#/definitions/uint32-array
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items:
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maximum: 255
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fan-supply:
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description: Phandle to the regulator that provides power to the fan.
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interrupts:
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description:
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This contains an interrupt specifier for each fan tachometer output
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connected to an interrupt source. The output signal must generate a
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defined number of interrupts per fan revolution, which require that
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it must be self resetting edge interrupts.
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maxItems: 1
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fan-stop-to-start-percent:
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description:
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Minimum fan RPM in percent to start when stopped.
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minimum: 0
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maximum: 100
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fan-stop-to-start-us:
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description:
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Time to wait in microseconds after start when stopped.
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pulses-per-revolution:
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description:
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Define the number of pulses per fan revolution for each tachometer
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input as an integer.
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 1
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maximum: 4
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default: 2
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pwms:
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description: The PWM that is used to control the fan.
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maxItems: 1
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"#cooling-cells": true
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required:
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- compatible
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- pwms
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additionalProperties: false
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examples:
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- |
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pwm-fan {
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compatible = "pwm-fan";
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cooling-levels = <0 102 170 230>;
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pwms = <&pwm 0 10000 0>;
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#cooling-cells = <2>;
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};
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thermal-zones {
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cpu_thermal: cpu-thermal {
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thermal-sensors = <&tmu 0>;
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polling-delay-passive = <0>;
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polling-delay = <0>;
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trips {
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cpu_alert1: cpu-alert1 {
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temperature = <100000>; /* millicelsius */
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hysteresis = <2000>; /* millicelsius */
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type = "passive";
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};
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};
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cooling-maps {
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map0 {
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trip = <&cpu_alert1>;
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cooling-device = <&fan0 0 1>;
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};
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};
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};
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};
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- |
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#include <dt-bindings/interrupt-controller/irq.h>
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pwm-fan {
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compatible = "pwm-fan";
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pwms = <&pwm 0 40000 0>;
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fan-supply = <®_fan>;
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interrupt-parent = <&gpio5>;
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interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
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pulses-per-revolution = <2>;
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};
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