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@xxxxxxxxxxxxxxxxxxxxxx/) > > 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 > >
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