Re: [PATCH v2] arm64: dts: renesas: r8a779g3: Add Argon40 fan HAT DTO to Retronix R-Car V4H Sparrow Hawk

[Marek Vasut <marek.vasut@mailbox.org>]

On 9/5/25 10:04 PM, Wolfram Sang wrote:

Hello Wolfram,

>>>> + * r8a779g3-sparrow-hawk$ grep -H . /sys/class/hwmon/hwmon?/name
>>>> + * /sys/class/hwmon/hwmon0/name:sensor1_thermal
>>>> + * /sys/class/hwmon/hwmon1/name:sensor2_thermal
>>>> + * /sys/class/hwmon/hwmon2/name:sensor3_thermal
>>>> + * /sys/class/hwmon/hwmon3/name:sensor4_thermal
>>>> + * /sys/class/hwmon/hwmon4/name:pwmfan
>>>> + *                       ^      ^^^^^^
>>>
>>> For me, the output looks different, though:
>>>
>>> /sys/class/hwmon/hwmon0/name:pwmfan
>>> /sys/class/hwmon/hwmon1/name:sensor1_thermal
>>> /sys/class/hwmon/hwmon2/name:sensor2_thermal
>>> /sys/class/hwmon/hwmon3/name:sensor3_thermal
>>> /sys/class/hwmon/hwmon4/name:sensor4_thermal
>>> /sys/class/hwmon/hwmon5/name:pwmfan
>>>
>>> hwmon0 is the Argon, hwmon5 the (unpopulated) on board connector.
>>>
>>> I hope the naming is stable, but in any case, the docs need to be
>>> reworked a little, I guess?
>>
>> The hwmon devices are allocated first come first served, so the list can
>> look different for you. You need to look up the fan you want to control, of
>> course. Look up by name is simplest, if there are more fans, it might be a
>> bit more involved to find the right one.
> 
> Exactly. This is why I would suggest to drop the '^^^^^' line from
> above. We definitely have two pwmfans with the above dtso. So finding
> the right one needs a second look anyhow. And while I think it is quite
> likely that the list of hwmon devices will look the same (I don't see a
> race condition which would make hwmon0 and hwmon5 swap), I agree we
> shouldn't rely on it. I would also think that we then maybe should
> change
> 
> 	echo 2 > /sys/class/hwmon/hwmon4/pwm1_enable
> 
> to
> 
> 	echo 2 > /sys/class/hwmon/hwmon<X>/pwm1_enable
> 
> or something? What do you think? Just suggestions, I am not really
> insisting. Well, maybe, about dropping the "^^^^" line ;)
I hope the V3 comment will be to your liking , as it addresses this 
part. I'll then send separate update for the native fan DTO once we 
agree on this wording.