tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: 21ef7b1e17d039053edaeaf41142423810572741 commit: 5145531be5fbad0e914d1dc1cbd392d7b756abaa [4727/8441] backlight: lp855x: Catch errors when changing brightness config: x86_64-buildonly-randconfig-r002-20230808 (https://download.01.org/0day-ci/archive/20230809/202308091728.NEJhgUPP-lkp@xxxxxxxxx/config) compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07) reproduce: (https://download.01.org/0day-ci/archive/20230809/202308091728.NEJhgUPP-lkp@xxxxxxxxx/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Closes: https://lore.kernel.org/oe-kbuild-all/202308091728.NEJhgUPP-lkp@xxxxxxxxx/ All warnings (new ones prefixed by >>): >> drivers/video/backlight/lp855x_bl.c:252:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] else if (lp->mode == REGISTER_BASED) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:55:28: note: expanded from macro 'if' #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) ) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:57:30: note: expanded from macro '__trace_if_var' #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/video/backlight/lp855x_bl.c:256:9: note: uninitialized use occurs here return ret; ^~~ drivers/video/backlight/lp855x_bl.c:252:7: note: remove the 'if' if its condition is always true else if (lp->mode == REGISTER_BASED) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:55:23: note: expanded from macro 'if' #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) ) ^ drivers/video/backlight/lp855x_bl.c:244:9: note: initialize the variable 'ret' to silence this warning int ret; ^ = 0 1 warning generated. vim +252 drivers/video/backlight/lp855x_bl.c 8cc9764c9c7d01 Kim, Milo 2012-12-17 239 7be865ab8634d4 Kim, Milo 2012-03-23 240 static int lp855x_bl_update_status(struct backlight_device *bl) 7be865ab8634d4 Kim, Milo 2012-03-23 241 { 7be865ab8634d4 Kim, Milo 2012-03-23 242 struct lp855x *lp = bl_get_data(bl); 61c1c6147f69d8 Sean Paul 2015-05-11 243 int brightness = bl->props.brightness; 5145531be5fbad Artur Weber 2023-07-14 244 int ret; 7be865ab8634d4 Kim, Milo 2012-03-23 245 9f0a511f4a227c Shingo Nakao 2013-07-02 246 if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK)) 61c1c6147f69d8 Sean Paul 2015-05-11 247 brightness = 0; 7be865ab8634d4 Kim, Milo 2012-03-23 248 61c1c6147f69d8 Sean Paul 2015-05-11 249 if (lp->mode == PWM_BASED) 5145531be5fbad Artur Weber 2023-07-14 250 ret = lp855x_pwm_ctrl(lp, brightness, 5145531be5fbad Artur Weber 2023-07-14 251 bl->props.max_brightness); 61c1c6147f69d8 Sean Paul 2015-05-11 @252 else if (lp->mode == REGISTER_BASED) 5145531be5fbad Artur Weber 2023-07-14 253 ret = lp855x_write_byte(lp, lp->cfg->reg_brightness, 5145531be5fbad Artur Weber 2023-07-14 254 (u8)brightness); 7be865ab8634d4 Kim, Milo 2012-03-23 255 5145531be5fbad Artur Weber 2023-07-14 256 return ret; 7be865ab8634d4 Kim, Milo 2012-03-23 257 } 7be865ab8634d4 Kim, Milo 2012-03-23 258 :::::: The code at line 252 was first introduced by commit :::::: 61c1c6147f69d8dea31fd133d2ec0b1594c9a3eb backlight: lp855x: Don't clear level on suspend/blank :::::: TO: Sean Paul <seanpaul@xxxxxxxxxxxx> :::::: CC: Lee Jones <lee.jones@xxxxxxxxxx> -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
