Messages in this thread | | | Date | Tue, 23 Apr 2024 15:45:12 +0700 | Subject | Re: [PATCH v2 3/3] dt-bindings: hwmon: max31790: Add maxim,pwmout-pin-as-tach-input property | From | Chanh Nguyen <> |
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On 16/04/2024 11:52, Chanh Nguyen wrote: > > > On 14/04/2024 13:07, Krzysztof Kozlowski wrote: >> On 14/04/2024 06:22, Chanh Nguyen wrote: >>> The max31790 supports six pins, which are dedicated PWM outputs. Any >>> of the >>> six PWM outputs can also be configured to serve as tachometer inputs, >>> allowing for up to 12 tachometer fans to be monitored. >>> >>> Add a new vendor-specific property, 'maxim,pwmout-pin-as-tach-input', >>> to allow PWMOUT to become a TACH input. >>> >>> 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. >>> >>> Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com> >>> --- >>> Changes in v2: >>> - Update the vendor property name to >>> "maxim,pwmout-pin-as-tach-input" [Rob] >>> - Update commit >>> message [Krzysztof] >> >> Please put binding before its user. >> > > Hi Krzysztof, I'll drop this [Path 3/3] in the patch series v3. > > My patch series will only be two patches. They are "dt-bindings: hwmon: > Add maxim max31790" and "hwmon: (max31790): Support config PWM output > becomes TACH" > >>> --- >>> .../devicetree/bindings/hwmon/maxim,max31790.yaml | 11 +++++++++++ >>> 1 file changed, 11 insertions(+) >>> >>> diff --git >>> a/Documentation/devicetree/bindings/hwmon/maxim,max31790.yaml >>> b/Documentation/devicetree/bindings/hwmon/maxim,max31790.yaml >>> index a561e5a3e9e4..2d4f50bc7c41 100644 >>> --- a/Documentation/devicetree/bindings/hwmon/maxim,max31790.yaml >>> +++ b/Documentation/devicetree/bindings/hwmon/maxim,max31790.yaml >>> @@ -30,6 +30,16 @@ properties: >>> resets: >>> maxItems: 1 >>> + maxim,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 >> >> tach-ch solves your case. You define which inputs should be used for >> tach. >> > > Agree Krzysztof. I'll use the tach-ch property from the fan-common.yaml > to solve my case. So I will not need to define a new vendor property as > "maxim,pwmout-pin-as-tach-input". I'll drop this [Path 3/3] in the patch > series v3. > > >> Best regards, >> Krzysztof >>
Hi Krzysztof,
I checked in the Documentation/devicetree/bindings/hwmon/fan-common.yaml. I found the tach-ch property, but it seems define the tach channel used for fan.
tach-ch: description: The tach channel used for the fan. $ref: /schemas/types.yaml#/definitions/uint8-array
In my purpose, I would like to configure the pwm output pins to become tachometer input pins by setting bit[0] in the Configuration Register.
I think a vendor property is suitable for this purpose. It is only available on specific MAX31790 fan controllers and not on other fan controller devices. So I think we can't use the "tach-ch" in fan-common.yaml.
I discussed it in the thread https://lore.kernel.org/lkml/ce8b2b49-b194-42f7-8f83-fcbf7b460970@amperemail.onmicrosoft.com/ , but I have not yet received Rob's response.
Please share your comment with me. I hope that will help us make a final decision.
Thank Krzysztof very much!
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