Hi Linus, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 291009f656e8eaebbdfd3a8d99f6b190a9ce9deb commit: e1c6edcbea13de025c3406645b4cce4ac3baf973 leds: rt8515: Add Richtek RT8515 LED driver date: 11 days ago config: i386-randconfig-a005-20210209 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout e1c6edcbea13de025c3406645b4cce4ac3baf973 # save the attached .config to linux build tree make W=1 ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): ld: drivers/leds/flash/leds-rt8515.o: in function `rt8515_v4l2_flash_release': drivers/leds/flash/leds-rt8515.c:216: undefined reference to `v4l2_flash_release' ld: drivers/leds/flash/leds-rt8515.o: in function `rt8515_probe': vim +354 drivers/leds/flash/leds-rt8515.c 275 276 static int rt8515_probe(struct platform_device *pdev) 277 { 278 struct device *dev = &pdev->dev; 279 struct fwnode_handle *child; 280 struct rt8515 *rt; 281 struct led_classdev *led; 282 struct led_classdev_flash *fled; 283 struct led_init_data init_data = {}; 284 struct v4l2_flash_config v4l2_sd_cfg = {}; 285 int ret; 286 287 rt = devm_kzalloc(dev, sizeof(*rt), GFP_KERNEL); 288 if (!rt) 289 return -ENOMEM; 290 291 rt->dev = dev; 292 fled = &rt->fled; 293 led = &fled->led_cdev; 294 295 /* ENF - Enable Flash line */ 296 rt->enable_flash = devm_gpiod_get(dev, "enf", GPIOD_OUT_LOW); 297 if (IS_ERR(rt->enable_flash)) 298 return dev_err_probe(dev, PTR_ERR(rt->enable_flash), 299 "cannot get ENF (enable flash) GPIO\n"); 300 301 /* ENT - Enable Torch line */ 302 rt->enable_torch = devm_gpiod_get(dev, "ent", GPIOD_OUT_LOW); 303 if (IS_ERR(rt->enable_torch)) 304 return dev_err_probe(dev, PTR_ERR(rt->enable_torch), 305 "cannot get ENT (enable torch) GPIO\n"); 306 307 child = fwnode_get_next_available_child_node(dev->fwnode, NULL); 308 if (!child) { 309 dev_err(dev, 310 "No fwnode child node found for connected LED.\n"); 311 return -EINVAL; 312 } 313 init_data.fwnode = child; 314 315 rt8515_determine_max_intensity(rt, child, "richtek,rfs-ohms", 316 "flash-max-microamp", 317 RT8515_FLASH_MAX, 318 &rt->flash_max_intensity); 319 rt8515_determine_max_intensity(rt, child, "richtek,rts-ohms", 320 "led-max-microamp", 321 RT8515_TORCH_MAX, 322 &rt->torch_max_intensity); 323 324 ret = fwnode_property_read_u32(child, "flash-max-timeout-us", 325 &rt->max_timeout); 326 if (ret) { 327 rt->max_timeout = RT8515_MAX_TIMEOUT_US; 328 dev_warn(dev, 329 "flash-max-timeout-us property missing\n"); 330 } 331 timer_setup(&rt->powerdown_timer, rt8515_powerdown_timer, 0); 332 rt8515_init_flash_timeout(rt); 333 334 fled->ops = &rt8515_flash_ops; 335 336 led->max_brightness = rt->torch_max_intensity; 337 led->brightness_set_blocking = rt8515_led_brightness_set; 338 led->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH; 339 340 mutex_init(&rt->lock); 341 342 platform_set_drvdata(pdev, rt); 343 344 ret = devm_led_classdev_flash_register_ext(dev, fled, &init_data); 345 if (ret) { 346 dev_err(dev, "can't register LED %s\n", led->name); 347 mutex_destroy(&rt->lock); 348 return ret; 349 } 350 351 rt8515_init_v4l2_flash_config(rt, &v4l2_sd_cfg); 352 353 /* Create a V4L2 Flash device if V4L2 flash is enabled */ 355 if (IS_ERR(rt->v4l2_flash)) { 356 ret = PTR_ERR(rt->v4l2_flash); 357 dev_err(dev, "failed to register V4L2 flash device (%d)\n", 358 ret); 359 /* 360 * Continue without the V4L2 flash 361 * (we still have the classdev) 362 */ 363 } 364 365 return 0; 366 } 367 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org