On Mon, 25 Jul 2016 13:19:47 +0800 Jisheng Zhang wrote:

Dear all,

On Fri, 22 Jul 2016 22:30:53 +0800 kbuild test robot wrote:

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Hi,

[auto build test WARNING on pm/linux-next]
[also build test WARNING on v4.7-rc7 next-20160722]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Jisheng-Zhang/PM-OPP-optimize-dev_pm_opp_set_rate-a-bit/20160722-205339
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: x86_64-allmodconfig (attached as .config)
compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   drivers/base/power/opp/core.c: In function 'dev_pm_opp_set_rate':  

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drivers/base/power/opp/core.c:666:3: warning: 'ou_volt_max' may be used uninitialized in this function [-Wmaybe-uninitialized]    

      _set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  

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drivers/base/power/opp/core.c:666:3: warning: 'ou_volt_min' may be used uninitialized in this function [-Wmaybe-uninitialized]
drivers/base/power/opp/core.c:666:3: warning: 'ou_volt' may be used uninitialized in this function [-Wmaybe-uninitialized]    

These warnings seem weired. We only use them when !IS_ERR(old_opp), and we
should already set them if !IS_ERR(old_opp). Another weired thing is if
we add something, printk e.g in _find_freq_ceil(), then these warnings disappear

Hmm, it looks that gcc will inline _find_freq_ceil(), then gcc can't
detect that ou_volt* are already set. Mark _find_freq_ceil() noinline would fix
the warnings

Thanks,
Jisheng

Could you please kindly give some suggestions about how to fix these warnings?