Messages in this thread | | | Date | Mon, 11 Mar 2024 10:52:17 -0700 | Subject | Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property | From | Guenter Roeck <> |
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On 3/11/24 10:34, Rob Herring wrote: > On Mon, Mar 11, 2024 at 06:13:47PM +0700, Chanh Nguyen wrote: >> Add pwmout-pin-as-tach-input property. >> >> Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com> >> --- >> Documentation/devicetree/bindings/hwmon/max31790.yaml | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/hwmon/max31790.yaml b/Documentation/devicetree/bindings/hwmon/max31790.yaml >> index 5a93e6bdebda..447cac17053a 100644 >> --- a/Documentation/devicetree/bindings/hwmon/max31790.yaml >> +++ b/Documentation/devicetree/bindings/hwmon/max31790.yaml >> @@ -25,6 +25,16 @@ properties: >> reg: >> maxItems: 1 >> >> + pwmout-pin-as-tach-input: >> + description: | >> + An array of six integers responds to six PWM channels for >> + configuring the pwm to tach mode. >> + When set to 0, the associated PWMOUT produces a PWM waveform for >> + control of fan speed. When set to 1, PWMOUT becomes a TACH input >> + $ref: /schemas/types.yaml#/definitions/uint8-array >> + maxItems: 6 >> + minItems: 6 > > Seems incomplete. For example, fan tachs have different number of > pulses per revolution, don't you need to know that too? >
Per Documentation/ABI/testing/sysfs-class-hwmon:
What: /sys/class/hwmon/hwmonX/fanY_pulses Description: Number of tachometer pulses per fan revolution.
Integer value, typically between 1 and 4.
RW
This value is a characteristic of the fan connected to the device's input, so it has to be set in accordance with the fan model.
Should only be created if the chip has a register to configure the number of pulses. In the absence of such a register (and thus attribute) the value assumed by all devices is 2 pulses per fan revolution.
We only expect the property (and attribute) to exist if the controller supports it.
Guenter
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