From: jszhang@marvell.com (Jisheng Zhang)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] PM / OPP: optimize dev_pm_opp_set_rate() a bit
Date: Mon, 25 Jul 2016 13:19:47 +0800 [thread overview]
Message-ID: <20160725131947.644e6166@xhacker> (raw)
In-Reply-To: <201607222230.DZObarhu%fengguang.wu@intel.com>
Dear all,
On Fri, 22 Jul 2016 22:30:53 +0800 kbuild test robot wrote:
> 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':
> >> 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);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> 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
Could you please kindly give some suggestions about how to fix these warnings?
Thanks,
Jisheng
>
> vim +/ou_volt_max +666 drivers/base/power/opp/core.c
>
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 650 if (freq < old_freq) {
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 651 ret = _set_opp_voltage(dev, reg, u_volt, u_volt_min,
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 652 u_volt_max);
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 653 if (ret)
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 654 goto restore_freq;
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 655 }
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 656
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 657 return 0;
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 658
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 659 restore_freq:
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 660 if (clk_set_rate(clk, old_freq))
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 661 dev_err(dev, "%s: failed to restore old-freq (%lu Hz)\n",
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 662 __func__, old_freq);
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 663 restore_voltage:
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 664 /* This shouldn't harm even if the voltages weren't updated earlier */
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 665 if (!IS_ERR(old_opp))
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 @666 _set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max);
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 667
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 668 return ret;
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 669 }
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 670 EXPORT_SYMBOL_GPL(dev_pm_opp_set_rate);
> 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 671
> 2c2709dc drivers/base/power/opp/core.c Viresh Kumar 2016-02-16 672 /* OPP-dev Helpers */
> 2c2709dc drivers/base/power/opp/core.c Viresh Kumar 2016-02-16 673 static void _kfree_opp_dev_rcu(struct rcu_head *head)
> 06441658 drivers/base/power/opp.c Viresh Kumar 2015-07-29 674 {
>
> :::::: The code at line 666 was first introduced by commit
> :::::: 6a0712f6f199e737aa5913d28ec4bd3a25de9660 PM / OPP: Add dev_pm_opp_set_rate()
>
> :::::: TO: Viresh Kumar <viresh.kumar@linaro.org>
> :::::: CC: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation
next prev parent reply other threads:[~2016-07-25 5:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-22 12:42 [PATCH] PM / OPP: optimize dev_pm_opp_set_rate() a bit Jisheng Zhang
2016-07-22 14:30 ` kbuild test robot
2016-07-25 5:19 ` Jisheng Zhang [this message]
2016-07-25 6:05 ` Jisheng Zhang
2016-07-22 16:21 ` Viresh Kumar
2016-07-25 5:12 ` Jisheng Zhang
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