From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH v1] Input: tegra-kbc - report wakeup key for some platforms. Date: Sun, 4 Dec 2011 20:27:36 -0800 Message-ID: <20111205042736.GA23733@core.coreip.homeip.net> References: <1322685811-14060-1-git-send-email-riyer@nvidia.com> <20111130212022.GB3108@core.coreip.homeip.net> <1FC56210173BB445BD77F608D6FB8D034F3D1BB4BD@HQMAIL03.nvidia.com> <20111201072649.GE16816@core.coreip.homeip.net> <1FC56210173BB445BD77F608D6FB8D034F3D1BB4C9@HQMAIL03.nvidia.com> <20111204085038.GC14593@core.coreip.homeip.net> <1323047897.3056.14.camel@riyer-dt2.nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1323047897.3056.14.camel-73r3X0hAYrhxWE4FnwvcdlaTQe2KTcn/@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: riyer Cc: "rydberg-Hk7bIW8heu4wFerOooGFRg@public.gmane.org" , Stephen Warren , Laxman Dewangan , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-input-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On Sun, Dec 04, 2011 at 05:18:17PM -0800, riyer wrote: > Hello Dmitry. > Please find replies inline. > > On Sun, 2011-12-04 at 00:50 -0800, Dmitry Torokhov wrote: > > Hi Rakesh, > > > > On Thu, Dec 01, 2011 at 01:09:59PM -0800, Rakesh Iyer wrote: > > > Hello Dmitry. > > > > > > Sorry for the wrap issue, my Outlook does not seem to obey the settings. > > > > > > I wanted to explain the tegra system resume path implementation so I can justify > > > why I am doing this complicated fix and why I feel it will guarantee the resume > > > is due to keypress. > > > > > > The tegra wake resume code is registered as a syscore ops. > > > When the system is resumed due to a wake event, the suspend_enter (after wakeup) > > > routine will invoke the tegra syscoreops_resume method and that routine will propagate > > > the wake event to the individual ISR's through genirq. > > > If kbc was wake source, kbc_isr will be invoked in this execution path. > > > > > > If system is resumed due to other reason, the tegra_syscoreops_resume code will not > > > find the event. > > > > Consider the following sequence: > > > > 1. Something other than keyboard generates wakeup event > > 2. It's IRQ fires up and gets serviced > At this point syscoreops_resume has finished all its wakeup processing. > > > 3. System starts resuming devices > > 4. User presses a key on the keypad while it is still suspended _and_ > > registered as a wakeup source > This will have no impact on the system and keypad ISR will not be > invoked. > > 5. Keypad's ISR runs as well and you decide that KEY_POWER should be > > reported even though keypad wasn't the real reason the system > > woke up. > The interrupt line we use to detect wakeup processing is the keypress > interrupt which is disabled and will never cause the ISR invocation from > a device interrupt(i.e. the PIC). > > In other words KBC isr gets invoked for 2 reasons > a) FIFO interrupt is generated, which will not happen as long as > scanning logic is disabled until kbc_resume executes. > b) The syscoreops_resume codepath calls into the ISR after finding KBC > was a wakesource. If this happens it will happen only when the kernel > resumes from its suspend code path. Is this code already in mainline or still somewhere else? > > > > Is this scenario not possible? > > > > Thanks. > > > With that being the case do you think the fix makes sense? OK, yes. I do not think it is that important if we occasionally report KEY_POWER even if KBC was not a true wakeup source but that's fine. Thanks. -- Dmitry