Hi, On 2/13/22 00:30, Andrey Smirnov wrote: <snip> >>> +static struct attribute *steamdeck_attributes[] = { >>> + &dev_attr_target_cpu_temp.attr, >>> + &dev_attr_gain.attr, >>> + &dev_attr_ramp_rate.attr, >>> + &dev_attr_hysteresis.attr, >>> + &dev_attr_maximum_battery_charge_rate.attr, >>> + &dev_attr_recalculate.attr, >>> + &dev_attr_power_cycle_display.attr, >>> + >>> + &dev_attr_led_brightness.attr, >> >> Have you considered using a led class device instead? I think that should >> work even without the ability to query the brightness. >> > > Not very seriously. Will take another look. > >> >>> + &dev_attr_content_adaptive_brightness.attr, >>> + &dev_attr_gamma_set.attr, >>> + &dev_attr_display_brightness.attr, >> >> Have you considered using a backlight class device? >> > > Ditto. Note that for both of these I would go a bit further then "have you considered?". Since you are implementing standardized userspace APIs here you *must* use the shared subsystem code for registering a LED resp backlight class device here so that everything is guaranteed to behave as expected by userspace. Regards, Hans