Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752343AbaANElO (ORCPT ); Mon, 13 Jan 2014 23:41:14 -0500 Received: from mail-qe0-f46.google.com ([209.85.128.46]:63770 "EHLO mail-qe0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751522AbaANElM (ORCPT ); Mon, 13 Jan 2014 23:41:12 -0500 Date: Mon, 13 Jan 2014 23:42:13 -0500 (EST) From: Vince Weaver To: Will Deacon cc: Vince Weaver , Chad Paradis , Peter Zijlstra , "linux-kernel@vger.kernel.org" , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , Stephane Eranian Subject: Re: [patch/rfc] perf on raspberry-pi without overflow interrupt In-Reply-To: <20140110100804.GB11045@mudshark.cambridge.arm.com> Message-ID: References: <20140108225315.GG31570@twins.programming.kicks-ass.net> <20140109101921.GA26435@mudshark.cambridge.arm.com> <20140110100804.GB11045@mudshark.cambridge.arm.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 10 Jan 2014, Will Deacon wrote: > In the absence of a core change, I think I'd rather have something like your > second patch, but without the extra no_overflow_irq field (you can check the > platform device, as I mentioned previously). Something like the following? It works on my rasp-pi, still waiting for the compile to finish on the pandaboard so I haven't verified that the has-working-interrupt case still works. --- Allow hardware perf_events to be enabled even if no overflow interrupt is available. Return EOPNOTSUPP if a sampling event is attempted and the interrupt is not available. This is necessary for access to hardware perf_events on the Raspberry-Pi (bcm2835). Signed-off-by: Vince Weaver diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c index bc3f2ef..e2c4aa2 100644 --- a/arch/arm/kernel/perf_event.c +++ b/arch/arm/kernel/perf_event.c @@ -397,7 +397,7 @@ __hw_perf_event_init(struct perf_event *event) */ hwc->config_base |= (unsigned long)mapping; - if (!hwc->sample_period) { + if (!is_sampling_event(event)) { /* * For non-sampling runs, limit the sample_period to half * of the counter width. That way, the new counter value @@ -407,6 +407,14 @@ __hw_perf_event_init(struct perf_event *event) hwc->sample_period = armpmu->max_period >> 1; hwc->last_period = hwc->sample_period; local64_set(&hwc->period_left, hwc->sample_period); + } else { + + /* + * If we have no PMU interrupt we cannot sample. + */ + if (platform_get_irq(armpmu->plat_device, 0) < 0) + return -EOPNOTSUPP; + } if (event->group_leader != event) { diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c index d85055c..7a84738 100644 --- a/arch/arm/kernel/perf_event_cpu.c +++ b/arch/arm/kernel/perf_event_cpu.c @@ -97,8 +97,8 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) irqs = min(pmu_device->num_resources, num_possible_cpus()); if (irqs < 1) { - pr_err("no irqs for PMUs defined\n"); - return -ENODEV; + printk_once("no irqs for PMUs defined, sampled events not supported\n"); + return 0; } for (i = 0; i < irqs; ++i) { -- 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/