From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Tue, 30 Jul 2013 10:47:15 +0200 Subject: Enable arm_global_timer for Zynq brakes boot In-Reply-To: <8d56935e-2a20-46c7-b80a-f779572dd839@CO1EHSMHS014.ehs.local> References: <20130717210417.GP13667@xsjandreislx> <51E72DCA.9070500@codeaurora.org> <51E7435B.3060605@codeaurora.org> <51ED8DF2.60600@codeaurora.org> <20130722201348.GI453@xsjandreislx> <0735ab8c-0f80-4b64-b2b2-8d4553482c2a@CO9EHSMHS013.ehs.local> <51F66565.7010600@linaro.org> <8d56935e-2a20-46c7-b80a-f779572dd839@CO1EHSMHS014.ehs.local> Message-ID: <51F77D93.4030505@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 07/30/2013 02:03 AM, S?ren Brinkmann wrote: > Hi Daniel, > > On Mon, Jul 29, 2013 at 02:51:49PM +0200, Daniel Lezcano wrote: > (snip) >> >> the CPUIDLE_FLAG_TIMER_STOP flag tells the cpuidle framework the local >> timer will be stopped when entering to the idle state. In this case, the >> cpuidle framework will call clockevents_notify(ENTER) and switches to a >> broadcast timer and will call clockevents_notify(EXIT) when exiting the >> idle state, switching the local timer back in use. > > I've been thinking about this, trying to understand how this makes my > boot attempts on Zynq hang. IIUC, the wrongly provided TIMER_STOP flag > would make the timer core switch to a broadcast device even though it > wouldn't be necessary. But shouldn't it still work? It sounds like we do > something useless, but nothing wrong in a sense that it should result in > breakage. I guess I'm missing something obvious. This timer system will > always remain a mystery to me. > > Actually this more or less leads to the question: What is this > 'broadcast timer'. I guess that is some clockevent device which is > common to all cores? (that would be the cadence_ttc for Zynq). Is the > hang pointing to some issue with that driver? If you look at the /proc/timer_list, which timer is used for broadcasting ? -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog