From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jisheng Zhang Subject: Re: [PATCH] PM / OPP: optimize dev_pm_opp_set_rate() a bit Date: Mon, 25 Jul 2016 13:19:47 +0800 Message-ID: <20160725131947.644e6166@xhacker> References: <1469191370-1285-1-git-send-email-jszhang@marvell.com> <201607222230.DZObarhu%fengguang.wu@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]:40324 "EHLO mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751869AbcGYFYa (ORCPT ); Mon, 25 Jul 2016 01:24:30 -0400 In-Reply-To: <201607222230.DZObarhu%fengguang.wu@intel.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: kbuild test robot , vireshk@kernel.org, nm@ti.com, sboyd@codeaurora.org, rjw@rjwysocki.net, gregkh@linuxfoundation.org, Arnd Bergmann Cc: kbuild-all@01.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org 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 > :::::: CC: Rafael J. Wysocki > > --- > 0-DAY kernel test infrastructure Open Source Technology Center > https://lists.01.org/pipermail/kbuild-all Intel Corporation