From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [Question] about patch: don't use [delayed_]work_pending() Date: Thu, 1 Sep 2016 14:45:03 -0400 Message-ID: <20160901184503.GD12660@htj.duckdns.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: qiaozhou Cc: linux-pm@vger.kernel.org, Wang Wilbur , Wu Gang , linux-kernel@vger.kernel.org List-Id: linux-pm@vger.kernel.org Hello, On Thu, Sep 01, 2016 at 05:09:36PM +0800, qiaozhou wrote: > In our system, we do cpu clock init in of_clk_init path, and use pm qos to > maintain cpu/cci clock. Firstly we init a CCI_CLK_QOS and set a default > value, then update CCI_CLK_QOS to limit CCI min frequency according to > current cpu frequency. Before calling pm_qos_update_request, irq is > disabled, but after the calling, irq is enabled in cancel_delayed_work_sync, > which causes some inconvenience before Before this patch is applied, it > checks pending work and won't do cancel_delayed_work_sync in this boot up > phase. So, cancel_delayed_work_sync() usually shouldn't be called with irq disabled as it's a possibly blocking call. > The simple calling sequence is like this: > > start_kernel -> of_clk_init -> cpu_clk_init -> pm_qos_add_request(xx, > default_value), > > then pm_qos_update_request. > > I don't know whether it's meaningful to still check pending work here, or > it's not suggested to use pm_qos_update_request in this early boot up phase. > Could you help to share some opinions? (I can fix this issue by adding the > current qos value directly instead of default value, though.) Hmmm... but I suppose this is super-early in the boot. Would it make sense to have a static variable (e.g. bool clk_fully_initailized) to gate the cancel_delayed_sync() call? Thanks. -- tejun