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> - if (get_brightness_range(caps, &min, &max)) { > + if (get_brightness_range(caps, &min, &max) && > + caps->ac_level > 0 && > + caps->dc_level > 0) { > if (power_supply_is_system_supplied() > 0) > props.brightness = DIV_ROUND_CLOSEST((max - min) * caps->ac_level, 100); > else