[arm-platforms:timers/tval-ectomy 2/17] drivers/clocksource/arm_arch_timer.c:156:3: warning: variable 'val' is used uninitialized whenever switch default is taken

[kernel test robot <lkp@intel.com>]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git timers/tval-ectomy
head:   c815d60a6292c90ea228c635b4150f022322908b
commit: 9c6e4aa680ebd5ad816fc8f97858ec6057362c9e [2/17] clocksource/arm_arch_timer: Drop CNT*_TVAL read accessors
config: arm64-randconfig-r026-20211010 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 30caca39f401ae17927439c0a0bd6d1b1916dd6a)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?id=9c6e4aa680ebd5ad816fc8f97858ec6057362c9e
        git remote add arm-platforms https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git
        git fetch --no-tags arm-platforms timers/tval-ectomy
        git checkout 9c6e4aa680ebd5ad816fc8f97858ec6057362c9e
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=arm64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/clocksource/arm_arch_timer.c:156:3: warning: variable 'val' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized]
                   default:
                   ^~~~~~~
   drivers/clocksource/arm_arch_timer.c:163:9: note: uninitialized use occurs here
           return val;
                  ^~~
   drivers/clocksource/arm_arch_timer.c:147:3: warning: variable 'val' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized]
                   default:
                   ^~~~~~~
   drivers/clocksource/arm_arch_timer.c:163:9: note: uninitialized use occurs here
           return val;
                  ^~~
   drivers/clocksource/arm_arch_timer.c:139:9: note: initialize the variable 'val' to silence this warning
           u32 val;
                  ^
                   = 0
   2 warnings generated.


vim +/val +156 drivers/clocksource/arm_arch_timer.c

f4e00a1a55c7f9 Marc Zyngier 2017-01-20  134  
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  135  static __always_inline
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  136  u32 arch_timer_reg_read(int access, enum arch_timer_reg reg,
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  137  			struct clock_event_device *clk)
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  138  {
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  139  	u32 val;
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  140  
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  141  	if (access == ARCH_TIMER_MEM_PHYS_ACCESS) {
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  142  		struct arch_timer *timer = to_arch_timer(clk);
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  143  		switch (reg) {
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  144  		case ARCH_TIMER_REG_CTRL:
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  145  			val = readl_relaxed(timer->base + CNTP_CTL);
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  146  			break;
0bc2c9327c236c Marc Zyngier 2021-09-20  147  		default:
0bc2c9327c236c Marc Zyngier 2021-09-20  148  			BUILD_BUG();
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  149  		}
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  150  	} else if (access == ARCH_TIMER_MEM_VIRT_ACCESS) {
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  151  		struct arch_timer *timer = to_arch_timer(clk);
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  152  		switch (reg) {
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  153  		case ARCH_TIMER_REG_CTRL:
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  154  			val = readl_relaxed(timer->base + CNTV_CTL);
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  155  			break;
0bc2c9327c236c Marc Zyngier 2021-09-20 @156  		default:
0bc2c9327c236c Marc Zyngier 2021-09-20  157  			BUILD_BUG();
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  158  		}
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  159  	} else {
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  160  		val = arch_timer_reg_read_cp15(access, reg);
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  161  	}
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  162  
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  163  	return val;
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  164  }
f4e00a1a55c7f9 Marc Zyngier 2017-01-20  165  

:::::: The code at line 156 was first introduced by commit
:::::: 0bc2c9327c236c28cdb2784d11ca349ef3b1ca0a clocksource/arm_arch_timer: Add build-time guards for unhandled register accesses

:::::: TO: Marc Zyngier <maz@kernel.org>
:::::: CC: Marc Zyngier <maz@kernel.org>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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