| Message ID | 20240414042246.8681-4-chanh@os.amperecomputing.com |
|---|---|
| State | New |
| Headers | show |
| Series | Update the max31790 driver | expand |
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 >
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!
On Tue, Apr 23, 2024 at 03:45:12PM +0700, Chanh Nguyen wrote: > > > 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. Can you explain why you think that only MAX31790 fan controllers are capable of an arbitrary mapping of PWM outputs to TACH inputs?
On 24/04/2024 00:02, Conor Dooley wrote: > [EXTERNAL EMAIL NOTICE: This email originated from an external sender. Please be mindful of safe email handling and proprietary information protection practices.] > Sorry Conor, there may be confusion here. I mean the mapping of the PWM output to the TACH input, which is on the MAX31790, and it is not sure a common feature on all fan controllers. I would like to open a discussion about whether we should use the tach-ch property on the fan-common.yaml I'm looking forward to hearing comments from everyone. For me, both tach-ch and vendor property are good. Thank you, Conor!
On 4/25/24 03:33, Chanh Nguyen wrote: > > > On 24/04/2024 00:02, Conor Dooley wrote: >> [EXTERNAL EMAIL NOTICE: This email originated from an external sender. Please be mindful of safe email handling and proprietary information protection practices.] >> > The quote doesn't make much sense. > Sorry Conor, there may be confusion here. I mean the mapping of the PWM output to the TACH input, which is on the MAX31790, and it is not sure a common feature on all fan controllers. > I think the term "mapping" is a bit confusing here. tach-ch, as I understand it, is supposed to associate a tachometer input with a pwm output, meaning the fan speed measured with the tachometer input is expected to change if the pwm output changes. On MAX31790, it is possible to configure a pwm output pin as tachometer input pin. That is something completely different. Also, the association is fixed. If the first pwm channel is used as tachometer channel, it would show up as 7th tachometer channel. If the 6th pwm channel is configured to be used as tachometer input, it would show up as 12th tachometer channel. Overall, the total number of channels on MAX31790 is always 12. 6 of them are always tachometer inputs, the others can be configured to either be a pwm output or a tachometer input. pwm outputs on MAX31790 are always tied to the matching tachometer inputs (pwm1 <--> tach1 etc) and can not be reconfigured, meaning tach-ch for channel X would always be X. > I would like to open a discussion about whether we should use the tach-ch property on the fan-common.yaml > > I'm looking forward to hearing comments from everyone. For me, both tach-ch and vendor property are good. > I am not even sure how to define tach-ch to mean "use the pwm output pin associated with this tachometer input channel not as pwm output but as tachometer input". That would be a boolean, not a number. Guenter
On Thu, Apr 25, 2024 at 05:46:02PM +0200, Krzysztof Kozlowski wrote: > On 25/04/2024 16:05, Guenter Roeck wrote: > > On 4/25/24 03:33, Chanh Nguyen wrote: > >> > >> > >> On 24/04/2024 00:02, Conor Dooley wrote: > >>> [EXTERNAL EMAIL NOTICE: This email originated from an external sender. Please be mindful of safe email handling and proprietary information protection practices.] > >>> > >> > > > > The quote doesn't make much sense. The reply is to me questioning part of their earlier reply: > 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. Can you explain why you think that only MAX31790 fan controllers are capable of an arbitrary mapping of PWM outputs to TACH inputs? > > > >> Sorry Conor, there may be confusion here. I mean the mapping of the PWM output to the TACH input, which is on the MAX31790, and it is not sure a common feature on all fan controllers. > >> > > > > I think the term "mapping" is a bit confusing here. > > > > tach-ch, as I understand it, is supposed to associate a tachometer input > > with a pwm output, meaning the fan speed measured with the tachometer input > > is expected to change if the pwm output changes. > > > > On MAX31790, it is possible to configure a pwm output pin as tachometer input pin. > > That is something completely different. Also, the association is fixed. > > If the first pwm channel is used as tachometer channel, it would show up as 7th > > tachometer channel. If the 6th pwm channel is configured to be used as tachometer > > input, it would show up as 12th tachometer channel. > > > > Overall, the total number of channels on MAX31790 is always 12. 6 of them > > are always tachometer inputs, the others can be configured to either be a > > pwm output or a tachometer input. > > > > pwm outputs on MAX31790 are always tied to the matching tachometer inputs > > (pwm1 <--> tach1 etc) and can not be reconfigured, meaning tach-ch for > > channel X would always be X. Are they? Granted, I probably didn't read this as well as you did, but figure 3, 4 5 & 6 seem to show mappings that are not 1:1, with PWMOUT1 controlling several fans, each of which report back via a different tach channel. I think the fan controller binding accounts for this though: the child nodes would reference the same PWM provider but have different tach-ch values. > > > >> I would like to open a discussion about whether we should use the tach-ch property on the fan-common.yaml > >> > >> I'm looking forward to hearing comments from everyone. For me, both tach-ch and vendor property are good. > >> > > > > I am not even sure how to define tach-ch to mean "use the pwm output pin > > associated with this tachometer input channel not as pwm output > > but as tachometer input". That would be a boolean, not a number. > > Thanks for explanation. So this is basically pin controller function > choice - kind of output or input, although not in terms of GPIO. > > Shouldn't we have then fan children which will be consumers of PWMs? In this case, the max31790 has the PWM hardware, so it would be the provider... > Having a consumer makes pin PWM output. Then tach-ch says which pins are > tachometer for given fan? Just like aspeed,g6-pwm-tach.yaml has? ...and it seems to me like there should be several fan child nodes as in the aspeed binding you mention here that are the consumers. The binding as written seems to only support a single fan.
On 25/04/2024 21:05, Guenter Roeck wrote: > On 4/25/24 03:33, Chanh Nguyen wrote: >> >> >> On 24/04/2024 00:02, Conor Dooley wrote: >>> [EXTERNAL EMAIL NOTICE: This email originated from an external >>> sender. Please be mindful of safe email handling and proprietary >>> information protection practices.] >>> >> > > The quote doesn't make much sense. > >> Sorry Conor, there may be confusion here. I mean the mapping of the >> PWM output to the TACH input, which is on the MAX31790, and it is not >> sure a common feature on all fan controllers. >> > > I think the term "mapping" is a bit confusing here. > > tach-ch, as I understand it, is supposed to associate a tachometer input > with a pwm output, meaning the fan speed measured with the tachometer input > is expected to change if the pwm output changes. > > On MAX31790, it is possible to configure a pwm output pin as tachometer > input pin. > That is something completely different. Also, the association is fixed. > If the first pwm channel is used as tachometer channel, it would show up > as 7th > tachometer channel. If the 6th pwm channel is configured to be used as > tachometer > input, it would show up as 12th tachometer channel. > > Overall, the total number of channels on MAX31790 is always 12. 6 of them > are always tachometer inputs, the others can be configured to either be a > pwm output or a tachometer input. Thank you, Guenter, for your explanation. That is also my understanding of the MAX31790 feature. So, I think we should introduce a vendor property to configure the pwm output pins to become tachometer input pins. We shouldn't use the tach-ch property. Because they are completely different, I think. What's your idea ? Please help share me, Guenter > > pwm outputs on MAX31790 are always tied to the matching tachometer inputs > (pwm1 <--> tach1 etc) and can not be reconfigured, meaning tach-ch for > channel X would always be X. > >> I would like to open a discussion about whether we should use the >> tach-ch property on the fan-common.yaml >> >> I'm looking forward to hearing comments from everyone. For me, both >> tach-ch and vendor property are good. >> > > I am not even sure how to define tach-ch to mean "use the pwm output pin > associated with this tachometer input channel not as pwm output > but as tachometer input". That would be a boolean, not a number. > Thank Guenter, I reviewed again the "tach-ch" property, which is used in the https://elixir.bootlin.com/linux/v6.9-rc6/source/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml#L68 and https://elixir.bootlin.com/linux/v6.9-rc6/source/drivers/hwmon/aspeed-g6-pwm-tach.c#L434 That is something completely different from my purpose. > Guenter >
On 5/5/24 03:08, Chanh Nguyen wrote: > > > On 25/04/2024 21:05, Guenter Roeck wrote: >> On 4/25/24 03:33, Chanh Nguyen wrote: >>> >>> >>> On 24/04/2024 00:02, Conor Dooley wrote: >>>> [EXTERNAL EMAIL NOTICE: This email originated from an external sender. Please be mindful of safe email handling and proprietary information protection practices.] >>>> >>> >> >> The quote doesn't make much sense. >> >>> Sorry Conor, there may be confusion here. I mean the mapping of the PWM output to the TACH input, which is on the MAX31790, and it is not sure a common feature on all fan controllers. >>> >> >> I think the term "mapping" is a bit confusing here. >> >> tach-ch, as I understand it, is supposed to associate a tachometer input >> with a pwm output, meaning the fan speed measured with the tachometer input >> is expected to change if the pwm output changes. >> >> On MAX31790, it is possible to configure a pwm output pin as tachometer input pin. >> That is something completely different. Also, the association is fixed. >> If the first pwm channel is used as tachometer channel, it would show up as 7th >> tachometer channel. If the 6th pwm channel is configured to be used as tachometer >> input, it would show up as 12th tachometer channel. >> >> Overall, the total number of channels on MAX31790 is always 12. 6 of them >> are always tachometer inputs, the others can be configured to either be a >> pwm output or a tachometer input. > > Thank you, Guenter, for your explanation. That is also my understanding of the MAX31790 feature. > > So, I think we should introduce a vendor property to configure the pwm output pins to become tachometer input pins. We shouldn't use the tach-ch property. Because they are completely different, I think. > > What's your idea ? Please help share me, Guenter > > >> >> pwm outputs on MAX31790 are always tied to the matching tachometer inputs >> (pwm1 <--> tach1 etc) and can not be reconfigured, meaning tach-ch for >> channel X would always be X. >> >>> I would like to open a discussion about whether we should use the tach-ch property on the fan-common.yaml >>> >>> I'm looking forward to hearing comments from everyone. For me, both tach-ch and vendor property are good. >>> >> >> I am not even sure how to define tach-ch to mean "use the pwm output pin >> associated with this tachometer input channel not as pwm output >> but as tachometer input". That would be a boolean, not a number. >> > > Thank Guenter, > > I reviewed again the "tach-ch" property, which is used in the https://elixir.bootlin.com/linux/v6.9-rc6/source/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml#L68 and https://elixir.bootlin.com/linux/v6.9-rc6/source/drivers/hwmon/aspeed-g6-pwm-tach.c#L434 > > That is something completely different from my purpose. > Based on its definition, tach-ch is associated with fans, and it looks like the .yaml file groups multiple sets of fans into a single fan node. In the simple case that would be tach-ch = <1> ... tach-ch = <12> or, if all fans are controlled by a single pwm tach-ch = <1 2 3 4 5 6 8 9 10 11 12> The existence of tachometer channel 7..12 implies that pwm channel (tachometer channel - 6) is used as tachometer channel. That should be sufficient to program the chip for that channel. All you'd have to do is to ensure that pwm channel "X" is not listed as tachometer channel "X + 6", and program pwm channel "X - 6" for tachometer channels 7..12 as tachometer channels. Hope this helps, Guenter
On 05/05/2024 22:40, Guenter Roeck wrote: > On 5/5/24 03:08, Chanh Nguyen wrote: >> >> >> On 25/04/2024 21:05, Guenter Roeck wrote: >>> On 4/25/24 03:33, Chanh Nguyen wrote: >>>> >>>> >>>> On 24/04/2024 00:02, Conor Dooley wrote: >>>>> [EXTERNAL EMAIL NOTICE: This email originated from an external >>>>> sender. Please be mindful of safe email handling and proprietary >>>>> information protection practices.] >>>>> >>>> >>> >>> The quote doesn't make much sense. >>> >>>> Sorry Conor, there may be confusion here. I mean the mapping of the >>>> PWM output to the TACH input, which is on the MAX31790, and it is >>>> not sure a common feature on all fan controllers. >>>> >>> >>> I think the term "mapping" is a bit confusing here. >>> >>> tach-ch, as I understand it, is supposed to associate a tachometer input >>> with a pwm output, meaning the fan speed measured with the tachometer >>> input >>> is expected to change if the pwm output changes. >>> >>> On MAX31790, it is possible to configure a pwm output pin as >>> tachometer input pin. >>> That is something completely different. Also, the association is fixed. >>> If the first pwm channel is used as tachometer channel, it would show >>> up as 7th >>> tachometer channel. If the 6th pwm channel is configured to be used >>> as tachometer >>> input, it would show up as 12th tachometer channel. >>> >>> Overall, the total number of channels on MAX31790 is always 12. 6 of >>> them >>> are always tachometer inputs, the others can be configured to either >>> be a >>> pwm output or a tachometer input. >> >> Thank you, Guenter, for your explanation. That is also my >> understanding of the MAX31790 feature. >> >> So, I think we should introduce a vendor property to configure the pwm >> output pins to become tachometer input pins. We shouldn't use the >> tach-ch property. Because they are completely different, I think. >> >> What's your idea ? Please help share me, Guenter >> >> >>> >>> pwm outputs on MAX31790 are always tied to the matching tachometer >>> inputs >>> (pwm1 <--> tach1 etc) and can not be reconfigured, meaning tach-ch for >>> channel X would always be X. >>> >>>> I would like to open a discussion about whether we should use the >>>> tach-ch property on the fan-common.yaml >>>> >>>> I'm looking forward to hearing comments from everyone. For me, both >>>> tach-ch and vendor property are good. >>>> >>> >>> I am not even sure how to define tach-ch to mean "use the pwm output pin >>> associated with this tachometer input channel not as pwm output >>> but as tachometer input". That would be a boolean, not a number. >>> >> >> Thank Guenter, >> >> I reviewed again the "tach-ch" property, which is used in the >> https://elixir.bootlin.com/linux/v6.9-rc6/source/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml#L68 and https://elixir.bootlin.com/linux/v6.9-rc6/source/drivers/hwmon/aspeed-g6-pwm-tach.c#L434 >> >> That is something completely different from my purpose. >> > > Based on its definition, tach-ch is associated with fans, and it looks > like the .yaml file groups multiple sets of fans into a single > fan node. > > In the simple case that would be > tach-ch = <1> > ... > tach-ch = <12> > > or, if all fans are controlled by a single pwm > tach-ch = <1 2 3 4 5 6 8 9 10 11 12> > > The existence of tachometer channel 7..12 implies that pwm channel > (tachometer > channel - 6) is used as tachometer channel. That should be sufficient to > program > the chip for that channel. All you'd have to do is to ensure that pwm > channel > "X" is not listed as tachometer channel "X + 6", and program pwm channel > "X - 6" > for tachometer channels 7..12 as tachometer channels. > Hi Guenter, I applied the patch [2/3] in my patch series (https://lore.kernel.org/lkml/20240414042246.8681-3-chanh@os.amperecomputing.com/) My device tree is configured as below, I would like to configure PWMOUT pins 5 and 6 to become the tachometer input pins. fan-controller@20 { compatible = "maxim,max31790"; reg = <0x20>; maxim,pwmout-pin-as-tach-input = /bits/ 8 <0 0 0 0 1 1>; }; The sysfs is generated by the max31790 driver are shown below. We can see the PWM5 and PWM6 are not visible, and the fan11 and fan12 are visible. And all FAN devices are on my system, which worked as expected. root@my-platform:/sys/class/hwmon/hwmon14# ls device fan12_input fan1_target fan2_target fan3_target fan4_target fan6_enable of_node pwm2 pwm4 fan11_fault fan1_enable fan2_enable fan3_enable fan4_enable fan5_enable fan6_fault power pwm2_enable pwm4_enable fan11_input fan1_fault fan2_fault fan3_fault fan4_fault fan5_fault fan6_input pwm1 pwm3 subsystem fan12_fault fan1_input fan2_input fan3_input fan4_input fan5_input name pwm1_enable pwm3_enable uevent Please share your comments! > Hope this helps, > Guenter >
On Wed, May 08, 2024 at 10:44:34AM +0700, Chanh Nguyen wrote: > On 05/05/2024 22:40, Guenter Roeck wrote: > > On 5/5/24 03:08, Chanh Nguyen wrote: > > > On 25/04/2024 21:05, Guenter Roeck wrote: > > > > On 4/25/24 03:33, Chanh Nguyen wrote: > > > > > > > > pwm outputs on MAX31790 are always tied to the matching > > > > tachometer inputs > > > > (pwm1 <--> tach1 etc) and can not be reconfigured, meaning tach-ch for > > > > channel X would always be X. > > > > > > > > > I would like to open a discussion about whether we should > > > > > use the tach-ch property on the fan-common.yaml > > > > > > > > > > I'm looking forward to hearing comments from everyone. For > > > > > me, both tach-ch and vendor property are good. > > > > > > > > > > > > > I am not even sure how to define tach-ch to mean "use the pwm output pin > > > > associated with this tachometer input channel not as pwm output > > > > but as tachometer input". That would be a boolean, not a number. > > > > > > > > > > Thank Guenter, > > > > > > I reviewed again the "tach-ch" property, which is used in the https://elixir.bootlin.com/linux/v6.9-rc6/source/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml#L68 > > > and https://elixir.bootlin.com/linux/v6.9-rc6/source/drivers/hwmon/aspeed-g6-pwm-tach.c#L434 > > > > > > That is something completely different from my purpose. > > > > > > > Based on its definition, tach-ch is associated with fans, and it looks > > like the .yaml file groups multiple sets of fans into a single > > fan node. > > > > In the simple case that would be > > tach-ch = <1> > > ... > > tach-ch = <12> > > > > or, if all fans are controlled by a single pwm > > tach-ch = <1 2 3 4 5 6 8 9 10 11 12> > > > > The existence of tachometer channel 7..12 implies that pwm channel > > (tachometer > > channel - 6) is used as tachometer channel. That should be sufficient to > > program > > the chip for that channel. All you'd have to do is to ensure that pwm > > channel > > "X" is not listed as tachometer channel "X + 6", and program pwm channel > > "X - 6" > > for tachometer channels 7..12 as tachometer channels. > > > > Hi Guenter, > > I applied the patch [2/3] in my patch series (https://lore.kernel.org/lkml/20240414042246.8681-3-chanh@os.amperecomputing.com/) > > My device tree is configured as below, I would like to configure PWMOUT pins > 5 and 6 to become the tachometer input pins. > > fan-controller@20 { > compatible = "maxim,max31790"; > reg = <0x20>; > maxim,pwmout-pin-as-tach-input = /bits/ 8 <0 0 0 0 1 1>; > }; Why are you still operating off a binding that looks like this? I thought that both I and Krzysztof told you to go and take a look at how the aspeed,g6-pwm-tach.yaml binding looped and do something similar here. You'd end up with something like: fan-controller@20 { compatible = "maxim,max31790"; reg = <0x20>; fan-0 { pwms = <&pwm-provider ...>; tach-ch = 6; }; fan-1 { pwms = <&pwm-provider ...>; tach-ch = 7; }; }; You can, as tach-ch or pwms do not need to be unique, set multiple channels up as using the same tachs and/or pwms. In the case of this particular fan controller, I think that the max31790 is actually the pwm provider so you'd modify it something like: pwm-provider: fan-controller@20 { compatible = "maxim,max31790"; reg = <0x20>; #pwm-cells = <N>; fan-0 { pwms = <&pwm-provider ...>; tach-ch = <6>; }; fan-1 { pwms = <&pwm-provider ...>; tach-ch = <7>; }; }; I just wrote this in my mail client's editor, so it may not be not valid, but it is how the fan bindings expect you to represent this kind of scenario. Cheers, Conor. > > The sysfs is generated by the max31790 driver are shown below. We can see > the PWM5 and PWM6 are not visible, and the fan11 and fan12 are visible. And > all FAN devices are on my system, which worked as expected. > > root@my-platform:/sys/class/hwmon/hwmon14# ls > device fan12_input fan1_target fan2_target fan3_target fan4_target > fan6_enable of_node pwm2 pwm4 > fan11_fault fan1_enable fan2_enable fan3_enable fan4_enable fan5_enable > fan6_fault power pwm2_enable pwm4_enable > fan11_input fan1_fault fan2_fault fan3_fault fan4_fault fan5_fault > fan6_input pwm1 pwm3 subsystem > fan12_fault fan1_input fan2_input fan3_input fan4_input fan5_input > name pwm1_enable pwm3_enable uevent > > Please share your comments! > > > Hope this helps, > > Guenter > >
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 + required: - compatible - reg @@ -48,5 +58,6 @@ examples: fan-controller@20 { compatible = "maxim,max31790"; reg = <0x20>; + maxim,pwmout-pin-as-tach-input = /bits/ 8 <0 0 0 0 1 1>; }; };
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] --- .../devicetree/bindings/hwmon/maxim,max31790.yaml | 11 +++++++++++ 1 file changed, 11 insertions(+)