[PATCH 0/3] Update the max31790 driver

[PATCH 0/3] Update the max31790 driver

[Chanh Nguyen]

Add the max31790 driver binding document and support pwmout-pin-as-tach-input
property for the max31790 driver.

Chanh Nguyen (3):
  dt-bindings: hwmon: Add maxim max31790 driver bindings
  hwmon: (max31790): Support config PWM output becomes TACH
  dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

 .../devicetree/bindings/hwmon/max31790.yaml   | 55 +++++++++++++++++++
 drivers/hwmon/max31790.c                      | 31 +++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/max31790.yaml

-- 
2.17.1

[PATCH 1/3] dt-bindings: hwmon: Add maxim max31790 driver bindings

[Chanh Nguyen]

Add a device tree bindings for max31790 device.

Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
---
 .../devicetree/bindings/hwmon/max31790.yaml   | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/max31790.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/max31790.yaml b/Documentation/devicetree/bindings/hwmon/max31790.yaml
new file mode 100644
index 000000000000..5a93e6bdebda
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/max31790.yaml
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/max31790.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: The Maxim MAX31790 Fan Controller
+
+maintainers:
+  - Jean Delvare <jdelvare@suse.com>
+  - Guenter Roeck <linux@roeck-us.net>
+
+description: >
+  The MAX31790 controls the speeds of up to six fans using six
+  independent PWM outputs. The desired fan speeds (or PWM duty cycles)
+  are written through the I2C interface.
+
+  Datasheets:
+    https://datasheets.maximintegrated.com/en/ds/MAX31790.pdf
+
+properties:
+  compatible:
+    const: maxim,max31790
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      max31790@20 {
+        compatible = "maxim,max31790";
+        reg = <0x20>;
+      };
+    };
-- 
2.17.1

[PATCH 2/3] hwmon: (max31790): Support config PWM output becomes TACH

[Chanh Nguyen]

PWMOUT pins on MAX31790 can be configured as a tachometer input pin by
setting bit[0] in the Configuration Register. When the bit[0] of a channel
is set, the PWMOUT pin becomes the tach input pin for the channel plus six.

This commit allows the kernel to set those pins when necessary if the
pwmout-pin-as-tach-input DT property exists.

Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
---
 drivers/hwmon/max31790.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c
index 3dc95196b229..33ca8d1721c0 100644
--- a/drivers/hwmon/max31790.c
+++ b/drivers/hwmon/max31790.c
@@ -12,6 +12,7 @@
 #include <linux/init.h>
 #include <linux/jiffies.h>
 #include <linux/module.h>
+#include <linux/property.h>
 #include <linux/slab.h>
 
 /* MAX31790 registers */
@@ -506,9 +507,12 @@ static int max31790_probe(struct i2c_client *client)
 {
 	struct i2c_adapter *adapter = client->adapter;
 	struct device *dev = &client->dev;
+	u8 pwmout_to_tach[NR_CHANNEL];
 	struct max31790_data *data;
 	struct device *hwmon_dev;
 	int err;
+	u8 tmp;
+	int i;
 
 	if (!i2c_check_functionality(adapter,
 			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
@@ -528,6 +532,33 @@ static int max31790_probe(struct i2c_client *client)
 	if (err)
 		return err;
 
+	if (device_property_present(dev, "pwmout-pin-as-tach-input")) {
+		err = device_property_read_u8_array(dev, "pwmout-pin-as-tach-input",
+						    pwmout_to_tach, NR_CHANNEL);
+		if (err) {
+			/* The pwmout-pin-as-tach-input is an array of six values */
+			dev_warn(dev, "The pwmout-pin-as-tach-input property exist but malform");
+		} else {
+			for (i = 0; i < NR_CHANNEL; i++) {
+				tmp = data->fan_config[i];
+				if (pwmout_to_tach[i])
+					data->fan_config[i] |= MAX31790_FAN_CFG_TACH_INPUT;
+				else
+					data->fan_config[i] &= ~(MAX31790_FAN_CFG_TACH_INPUT);
+
+				if (tmp != data->fan_config[i]) {
+					err = i2c_smbus_write_byte_data(client,
+									MAX31790_REG_FAN_CONFIG(i),
+									data->fan_config[i]);
+					if (err < 0)
+						dev_warn(dev,
+							 "Fail to apply fan configuration at channel %d",
+							 i);
+				}
+			}
+		}
+	}
+
 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
 							 data,
 							 &max31790_chip_info,
-- 
2.17.1

[PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

[Chanh Nguyen]

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
+
 required:
   - compatible
   - reg
@@ -40,5 +50,6 @@ examples:
       max31790@20 {
         compatible = "maxim,max31790";
         reg = <0x20>;
+        pwmout-pin-as-tach-input = /bits/ 8 <0 0 0 0 1 1>;
       };
     };
-- 
2.17.1

Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

[Rob Herring]

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? 

There's a common fan binding now (or pending). You should use that and 
this property won't be needed.

Rob

Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

[Guenter Roeck]

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

Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

[Chanh Nguyen]

On 11/03/2024 23:56, Krzysztof Kozlowski wrote:
> On 11/03/2024 12:13, Chanh Nguyen wrote:
>> Add pwmout-pin-as-tach-input property.
> 
> Why is this split from original binding? This does not make much
> sense... Add complete hardware description.
> 

Ok Krzysztof, I will merg the "[PATCH 1/3] dt-bindings: hwmon: Add maxim 
max31790 driver bindings" commit and "[PATCH 3/3] dt-bindings: hwmon: 
max31790: Add pwmout-pin-as-tach-input property" commit.

>>
>> 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
> 
> No vendor prefix, so generic property... but where is it defined?
> 

Thank Krzysztof! It is not generic property, I'll add the vendor prefix.

I'll update the "pwmout-pin-as-tach-input" to 
"maxim,pwmout-pin-as-tach-input" at v2.

> 
> Best regards,
> Krzysztof
> 

Re: [PATCH 1/3] dt-bindings: hwmon: Add maxim max31790 driver bindings

[Chanh Nguyen]

On 11/03/2024 23:55, Krzysztof Kozlowski wrote:
> On 11/03/2024 12:13, Chanh Nguyen wrote:
>> Add a device tree bindings for max31790 device.
> 
> Subject: drop "driver", bindings are about hardware.
> 

Yes, I'll drop "driver" at v2 updating.

> It does not look like you tested the bindings, at least after quick
> look. Please run `make dt_binding_check` (see
> Documentation/devicetree/bindings/writing-schema.rst for instructions).
> Maybe you need to update your dtschema and yamllint.
> 


I tested the binding, I didn't see any warning/error log. Please review 
my logs as below

=> make dt_binding_check DT_SCHEMA_FILES=/hwmon/max31790.yaml
make[1]: Entering directory '/DISK4T/work/community/linux/out'
   DTEX    Documentation/devicetree/bindings/hwmon/max31790.example.dts
   DTC_CHK Documentation/devicetree/bindings/hwmon/max31790.example.dtb
make[1]: Leaving directory '/DISK4T/work/community/linux/out'

>>
>> Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
>> ---
>>   .../devicetree/bindings/hwmon/max31790.yaml   | 44 +++++++++++++++++++
>>   1 file changed, 44 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/hwmon/max31790.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/hwmon/max31790.yaml b/Documentation/devicetree/bindings/hwmon/max31790.yaml
>> new file mode 100644
>> index 000000000000..5a93e6bdebda
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/hwmon/max31790.yaml
> 
> Filename like compatible.

Yes, I'll update that in v2

> 
>> @@ -0,0 +1,44 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/hwmon/max31790.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: The Maxim MAX31790 Fan Controller
>> +
>> +maintainers:
>> +  - Jean Delvare <jdelvare@suse.com>
>> +  - Guenter Roeck <linux@roeck-us.net>
> 
> You should have here someone responsible for hardware, not subsystem
> maintainers.
> 

Hi Krzysztof,
I checked the history of the drivers/hwmon/max31790.c and see Guenter 
Roeck <linux@roeck-us.net> as an important maintainer. I saw many 
commits from him. So, I add him to maintainer list.

>> +
>> +description: >
>> +  The MAX31790 controls the speeds of up to six fans using six
>> +  independent PWM outputs. The desired fan speeds (or PWM duty cycles)
>> +  are written through the I2C interface.
>> +
>> +  Datasheets:
>> +    https://datasheets.maximintegrated.com/en/ds/MAX31790.pdf
>> +
>> +properties:
>> +  compatible:
>> +    const: maxim,max31790
>> +
>> +  reg:
>> +    maxItems: 1
> 
> That's weirdly empty.
> 

Hi Krzysztof,
I have not yet understood your comment here. Please help give more 
details for my missing! Thank Krzysztof!
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +
> 
> You miss allOf: with $ref to fan controller schema.
> 

Thank Krzysztof,
I'll add the allOf at v2.

>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    i2c {
>> +      #address-cells = <1>;
>> +      #size-cells = <0>;
>> +
>> +      max31790@20 {
> 
> Node names should be generic. See also an explanation and list of
> examples (not exhaustive) in DT specification:
> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
> 

I suggest some node names, such as "i2c-fan" or "fan-controller" . Can 
you please share your ideas with me!

> 
> Best regards,
> Krzysztof
> 

Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

[Chanh Nguyen]

On 12/03/2024 00:34, 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?
> 
> There's a common fan binding now (or pending). You should use that and
> this property won't be needed.
> 
> Rob

Thank Rob,

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

I would like to define a new vendor property to configure the PWM-OUT 
pin to become a TACH-IN pin. So I introduce the 
"maxim,pwmout-pin-as-tach-input" property. Please help me share your 
comments!

Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

[Chanh Nguyen]

On 12/03/2024 00:52, Guenter Roeck wrote:
> 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
> 

Hi Guenter and Rob,
Most general-purpose brushless DC fans produce two tachometer pulses per 
revolution. My fan devices also produce two tachometer pulses per 
revolution.

In max31790.c, I saw the formula that is used to calculate TACH Count 
Registers, which defines the pulses per revolution as 2

	#define RPM_TO_REG(rpm, sr)             ((60 * (sr) * 8192) / ((rpm) * 2))

Do you think we should support the pulses-per-revolution property in 
this case?

Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

[Chanh Nguyen]

On 18/03/2024 17:02, Krzysztof Kozlowski wrote:
> On 18/03/2024 10:48, Chanh Nguyen wrote:
>>
>>
>> On 11/03/2024 23:56, Krzysztof Kozlowski wrote:
>>> On 11/03/2024 12:13, Chanh Nguyen wrote:
>>>> Add pwmout-pin-as-tach-input property.
>>>
>>> Why is this split from original binding? This does not make much
>>> sense... Add complete hardware description.
>>>
>>
>> Ok Krzysztof, I will merg the "[PATCH 1/3] dt-bindings: hwmon: Add maxim
>> max31790 driver bindings" commit and "[PATCH 3/3] dt-bindings: hwmon:
>> max31790: Add pwmout-pin-as-tach-input property" commit.
> 
> Later I checked your driver code and this explains a bit. However first
> patch should explain that instead. The split is fine, but just lack of
> rationale is confusing.
> 

Thank Krzysztof. I'll try to explain in detail each patch in v2.

> 
>>
>>>>
>>>> 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
>>>
>>> No vendor prefix, so generic property... but where is it defined?
>>>
>>
>> Thank Krzysztof! It is not generic property, I'll add the vendor prefix.
>>
>> I'll update the "pwmout-pin-as-tach-input" to
>> "maxim,pwmout-pin-as-tach-input" at v2.
> 
> Except that you should really look into common properties and use them.
> Or explain why do you need new property?
> 
> Best regards,
> Krzysztof
> 

I'm also discussing with Rob Herring that on patch 3/3, I checked in the 
Documentation/devicetree/bindings/hwmon/fan-common.yaml. I found the 
tach-ch property, but it seems to define the tach channel used for the 
fan. It does not match my purpose. I want to configure the PWM-OUT pin 
to become a TACH-IN pin. I wonder if I can use the tach-ch property for 
my purpose.

Re: [PATCH 1/3] dt-bindings: hwmon: Add maxim max31790 driver bindings

[Chanh Nguyen]

On 18/03/2024 17:00, Krzysztof Kozlowski wrote:
> On 18/03/2024 10:51, Chanh Nguyen wrote:
>>
>>> It does not look like you tested the bindings, at least after quick
>>> look. Please run `make dt_binding_check` (see
>>> Documentation/devicetree/bindings/writing-schema.rst for instructions).
>>> Maybe you need to update your dtschema and yamllint.
>>>
>>
>>
>> I tested the binding, I didn't see any warning/error log. Please review
>> my logs as below
> 
> Hm, I don't remember what brought my attention to possible error. Maybe
> I mistyped my template.
> 
>>
>> => make dt_binding_check DT_SCHEMA_FILES=/hwmon/max31790.yaml
>> make[1]: Entering directory '/DISK4T/work/community/linux/out'
>>     DTEX    Documentation/devicetree/bindings/hwmon/max31790.example.dts
>>     DTC_CHK Documentation/devicetree/bindings/hwmon/max31790.example.dtb
>> make[1]: Leaving directory '/DISK4T/work/community/linux/out'
>>
>>>>
>>>> Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
>>>> ---
>>>>    .../devicetree/bindings/hwmon/max31790.yaml   | 44 +++++++++++++++++++
>>>>    1 file changed, 44 insertions(+)
>>>>    create mode 100644 Documentation/devicetree/bindings/hwmon/max31790.yaml
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/hwmon/max31790.yaml b/Documentation/devicetree/bindings/hwmon/max31790.yaml
>>>> new file mode 100644
>>>> index 000000000000..5a93e6bdebda
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/hwmon/max31790.yaml
>>>
>>> Filename like compatible.
>>
>> Yes, I'll update that in v2
>>
>>>
>>>> @@ -0,0 +1,44 @@
>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: http://devicetree.org/schemas/hwmon/max31790.yaml#
>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>> +
>>>> +title: The Maxim MAX31790 Fan Controller
>>>> +
>>>> +maintainers:
>>>> +  - Jean Delvare <jdelvare@suse.com>
>>>> +  - Guenter Roeck <linux@roeck-us.net>
>>>
>>> You should have here someone responsible for hardware, not subsystem
>>> maintainers.
>>>
>>
>> Hi Krzysztof,
>> I checked the history of the drivers/hwmon/max31790.c and see Guenter
>> Roeck <linux@roeck-us.net> as an important maintainer. I saw many
>> commits from him. So, I add him to maintainer list.
> 
> OK
> 
>>
>>>> +
>>>> +description: >
>>>> +  The MAX31790 controls the speeds of up to six fans using six
>>>> +  independent PWM outputs. The desired fan speeds (or PWM duty cycles)
>>>> +  are written through the I2C interface.
>>>> +
>>>> +  Datasheets:
>>>> +    https://datasheets.maximintegrated.com/en/ds/MAX31790.pdf
>>>> +
>>>> +properties:
>>>> +  compatible:
>>>> +    const: maxim,max31790
>>>> +
>>>> +  reg:
>>>> +    maxItems: 1
>>>
>>> That's weirdly empty.
>>>
>>
>> Hi Krzysztof,
>> I have not yet understood your comment here. Please help give more
>> details for my missing! Thank Krzysztof!
> 
> I expect many more properties of a fan controller. Resources (clocks,
> PWMs, supplies) and FAN specific properties.
> 

Hi Krzysztof,

I'm creating a base binding document for the max31790 driver. I'm basing 
it on the drivers/hwmon/max31790.c. Currently, the max31790.c driver has 
not yet implemented other properties, such as clocks, fan-supply, pwms, 
etc. So I just introduced the "compatible" and "reg" properties.

In the near future, if any other properties are necessary, I think we 
will implement them in drivers/hwmon/max31790.c then update this binding 
document.

I look at other binding documents, I also see something similar. They 
just introduce the "compatible" and "reg" properties.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/hwmon/adi,max31760.yaml 


https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/hwmon/adt7475.yaml

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/hwmon/adi,ad741x.yaml

This is only my view. It's a pleasure to hear your advice. Thanks!


> 
>>>> +
>>>> +required:
>>>> +  - compatible
>>>> +  - reg
>>>> +
>>>
>>> You miss allOf: with $ref to fan controller schema.
>>>
>>
>> Thank Krzysztof,
>> I'll add the allOf at v2.
>>
>>>> +additionalProperties: false
>>>> +
>>>> +examples:
>>>> +  - |
>>>> +    i2c {
>>>> +      #address-cells = <1>;
>>>> +      #size-cells = <0>;
>>>> +
>>>> +      max31790@20 {
>>>
>>> Node names should be generic. See also an explanation and list of
>>> examples (not exhaustive) in DT specification:
>>> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
>>>
>>
>> I suggest some node names, such as "i2c-fan" or "fan-controller" . Can
>> you please share your ideas with me!
> 
> Look at recent commits and patches for similar type of a device.
> 

Hi Krzysztof,

I checked on recent commits and found something of a similar type.

adi,max31760.yaml
         fan-controller@50 {
             reg = <0x50>;
             compatible = "adi,max31760";
         };

hpe,gxp-fan-ctrl.yaml
     fan-controller@1000c00 {
       compatible = "hpe,gxp-fan-ctrl";
       reg = <0x1000c00 0x200>, <0xd1000000 0xff>, <0x80200000 0x100000>;
       reg-names = "base", "pl", "fn2";
     };


adi,axi-fan-control.yaml
         axi_fan_control: axi-fan-control@80000000 {
             compatible = "adi,axi-fan-control-1.00.a";
             reg = <0x0 0x80000000 0x10000>;
             clocks = <&clk 71>;
             interrupts = <0 110 0>;
             pulses-per-revolution = <2>;
         };

I think "fan-controller" is a good node name. Do you think so?

> Best regards,
> Krzysztof
> 

Re: [PATCH 1/3] dt-bindings: hwmon: Add maxim max31790 driver bindings

[Chanh Nguyen]

On 25/03/2024 15:32, Krzysztof Kozlowski wrote:
> On 22/03/2024 10:53, Chanh Nguyen wrote:
>>>>>
>>>>
>>>> Hi Krzysztof,
>>>> I have not yet understood your comment here. Please help give more
>>>> details for my missing! Thank Krzysztof!
>>>
>>> I expect many more properties of a fan controller. Resources (clocks,
>>> PWMs, supplies) and FAN specific properties.
>>>
>>
>> Hi Krzysztof,
>>
>> I'm creating a base binding document for the max31790 driver. I'm basing
>> it on the drivers/hwmon/max31790.c. Currently, the max31790.c driver has
> 
> Binding should be based on device (e.g. its datasheet), not the driver.
> 

Thank Krzysztof,
I'm reading the writing-bindings.rst and I got it for now. I'll make 
complete binding in patch v2.

I am very pleased to hear your comments.

>> not yet implemented other properties, such as clocks, fan-supply, pwms,
>> etc. So I just introduced the "compatible" and "reg" properties.
>>
>> In the near future, if any other properties are necessary, I think we
>> will implement them in drivers/hwmon/max31790.c then update this binding
>> document.
> 
> Please instead read:
> Documentation/devicetree/bindings/writing-bindings.rst
> 
>>
>> I look at other binding documents, I also see something similar. They
>> just introduce the "compatible" and "reg" properties.
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/hwmon/adi,max31760.yaml
> 
> Maybe these devices are similar, maybe not. This should not be excuse to
> come with really incomplete binding.
> 
> ...
> 
>> I think "fan-controller" is a good node name. Do you think so?
>>
> 
> Yes.
> 
> Best regards,
> Krzysztof
> 

Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add pwmout-pin-as-tach-input property

[Chanh Nguyen]

On 18/03/2024 16:53, Chanh Nguyen wrote:
> 
> 
> On 12/03/2024 00:34, 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?
>>
>> There's a common fan binding now (or pending). You should use that and
>> this property won't be needed.
>>
>> Rob
> 
> Thank Rob,
> 
> 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
> 
> I would like to define a new vendor property to configure the PWM-OUT 
> pin to become a TACH-IN pin. So I introduce the 
> "maxim,pwmout-pin-as-tach-input" property. Please help me share your 
> comments!

Hi Guenter and Rob,

I'm preparing for patch v2. I'm looking forward to hear your advice. 
Should I use the "tach-ch" property (a common fan property) or define 
new vendor property ("maxim,pwmout-pin-as-tach-input") for my purpose?

Thank you very much!
Chanh