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@xxxxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxxxxxxxxxxxxxxxx/
, 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!
