Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758041Ab3GaQ1M (ORCPT ); Wed, 31 Jul 2013 12:27:12 -0400 Received: from co1ehsobe001.messaging.microsoft.com ([216.32.180.184]:41536 "EHLO co1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752816Ab3GaQ1K convert rfc822-to-8bit (ORCPT ); Wed, 31 Jul 2013 12:27:10 -0400 X-Forefront-Antispam-Report: CIP:149.199.60.83;KIP:(null);UIP:(null);IPV:NLI;H:xsj-gw1;RD:unknown-60-83.xilinx.com;EFVD:NLI X-SpamScore: -3 X-BigFish: VPS-3(zzbb2dI98dI9371Ic89bh1432Izz1f42h208ch1ee6h1de0h1fdah2073h1202h1e76h1d1ah1d2ah1fc6hzzz2fh95h668h839h93fhd24hf0ah119dh1288h12a5h12a9h12bdh137ah13b6h1441h14ddh1504h1537h153bh162dh1631h1758h18e1h1946h19b5h1b0ah1d0ch1d2eh1d3fh1dfeh1dffh1e1dh906i1155h192ch) Date: Wed, 31 Jul 2013 09:26:55 -0700 From: =?utf-8?B?U8O2cmVu?= Brinkmann To: Daniel Lezcano CC: Stephen Boyd , John Stultz , Thomas Gleixner , Stuart Menefy , Russell King , Michal Simek , , Subject: Re: Enable arm_global_timer for Zynq brakes boot References: <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> <51F77D93.4030505@linaro.org> <51F8BC5D.80605@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: <51F8BC5D.80605@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-RCIS-Action: ALLOW Message-ID: <2ebbb5cd-2755-4082-b434-d276e7225de5@CO1EHSMHS024.ehs.local> Content-Transfer-Encoding: 8BIT X-OriginatorOrg: xilinx.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3416 Lines: 74 On Wed, Jul 31, 2013 at 09:27:25AM +0200, Daniel Lezcano wrote: > On 07/31/2013 12:34 AM, Sören Brinkmann wrote: > > On Tue, Jul 30, 2013 at 10:47:15AM +0200, Daniel Lezcano wrote: > >> On 07/30/2013 02:03 AM, Sören 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 ? > > > > So, the correct run results (full output attached). > > > > The vanilla kernel uses the twd timers as local timers and the TTC as > > broadcast device: > > Tick Device: mode: 1 > > Broadcast device > > Clock Event Device: ttc_clockevent > > > > When I remove the offending CPUIDLE flag and add the DT fragment to > > enable the global timer, the twd timers are still used as local timers > > and the broadcast device is the global timer: > > Tick Device: mode: 1 > > Broadcast device > > Clock Event Device: arm_global_timer > > > > Again, since boot hangs in the actually broken case, I don't see way to > > obtain this information for that case. > > Hmm, interesting. Can you give the ouput of /proc/interrupts also with > the global timer ? Sure: # cat /proc/interrupts CPU0 CPU1 27: 14 1 GIC 27 gt 29: 841 843 GIC 29 twd 43: 0 0 GIC 43 ttc_clockevent 82: 563 0 GIC 82 xuartps IPI0: 0 0 CPU wakeup interrupts IPI1: 0 0 Timer broadcast interrupts IPI2: 1266 1330 Rescheduling interrupts IPI3: 0 0 Function call interrupts IPI4: 34 59 Single function call interrupts IPI5: 0 0 CPU stop interrupts Err: 0 Sören -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/