BLT_PWM_DUTY_MASK
bl_data->current_brightness = FIELD_GET(BLT_PWM_DUTY_MASK, reply_buf[0]);
cmd_buf[1] = (reply_buf[0] & ~BLT_PWM_DUTY_MASK) |
FIELD_PREP(BLT_PWM_DUTY_MASK, brightness);
bl_data->current_brightness = reply_buf[0] & BLT_PWM_DUTY_MASK;