Re: [PATCH 1/1] hwmon: (applesmc) Convert to hwmon_device_register_with_info

[Guenter Roeck]

On 7/10/26 14:10, Armin Wolf wrote:
> Am 10.07.26 um 16:01 schrieb Guenter Roeck:
>
> > On 7/10/26 05:32, Shih-Yuan Lee wrote:
> > > The legacy hwmon_device_register() function is deprecated and triggers a
> > > warning in dmesg during driver initialization:
> > >
> > > [   24.706091] applesmc: key=620 fan=0 temp=37 index=36 acc=0 lux=2 kbd=0
> > > [   24.706270] applesmc applesmc.768: hwmon_device_register() is deprecated. Please convert the driver to use hwmon_device_register_with_info().
> > >
> > > To silence this warning, convert the driver to use the modern
> > > hwmon_device_register_with_info() API.
> > >
> > > Because the driver creates all its sysfs attributes dynamically on the platform
> > > device, we define a minimal struct hwmon_chip_info with a single temperature
> > > channel and implement a visibility callback that returns 0 (hidden) for it.
> > > This satisfies the new API requirements while keeping all existing sysfs paths
> > > and attributes completely unchanged, ensuring backwards compatibility.
> >
> > Novel, but that would completely defeat the purpose of the new API.
> > NACK.
> >
> > Guenter 
>
> Agree, this deprecation warning should not be silenced by using cheap tricks.
>
> Lee, i think instead of abusing the hwmon_device_register_with_info() to emulate the
> behavior of the old API, i suggest that you use the new API to replace these two calls
> to applesmc_create_nodes():
>
> ret = applesmc_create_nodes(fan_group, smcreg.fan_count);
> if (ret)
>          goto out_info;
>
> ret = applesmc_create_nodes(temp_group, smcreg.index_count);
> if (ret)
>          oto out_fans;
>
> Basically, you need to dynamically allocate a struct hwmon_channel_info each for the fan
> and temperature sensors. Then you basically use the new API to create the standard attributes
> for you, while the non-standard attributes are still created manually and passed using the
> extra_groups parameter.
>
> The non-standard attributes are:
> - fanX_safe
> - fanX_output (should be renamed to fanX_target to comply with the standard sysfs ABI)
> - fanX_manual (should be renamed to pwmX_enable to comply with the standard sysfs ABI)
>
> This changes are not exactly trivial and should be tested on real hardware. You should
> only attempt this if you have access to a compatible device for testing.

Exactly. Other drivers, such as the asus-ec-sensors driver, use the same approach.

Thanks,
Guenter