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

[Wolfram Sang <wsa+renesas@sang-engineering.com>]

Hi Marek,

> > > + * 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 ;)

Happy hacking,

   Wolfram