From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vincent Pelletier Subject: Re: leds-gpio on x86 Date: Tue, 18 Aug 2015 09:32:26 +0200 Message-ID: <20150818093226.3db0b553@x2> References: <20150805220948.3984f19c@x2> <20150806165924.GY1540@lahna.fi.intel.com> <20150806191727.0bf87a3a@x2> <20150806173558.GZ1540@lahna.fi.intel.com> <20150806201820.5ca0764d@x2> <20150807105745.GB1540@lahna.fi.intel.com> <20150808140656.6b81d3b9@x2> <20150811120038.GF1541@lahna.fi.intel.com> <20150811194256.08816c63@x2> <20150812125314.GS1541@lahna.fi.intel.com> <20150815123640.45a5b9bf@x2> <20150817230823.61de477a@x2> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f176.google.com ([209.85.212.176]:38214 "EHLO mail-wi0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079AbbHRHc3 (ORCPT ); Tue, 18 Aug 2015 03:32:29 -0400 Received: by wicja10 with SMTP id ja10so99973064wic.1 for ; Tue, 18 Aug 2015 00:32:28 -0700 (PDT) In-Reply-To: <20150817230823.61de477a@x2> Sender: linux-leds-owner@vger.kernel.org List-Id: linux-leds@vger.kernel.org To: Mika Westerberg Cc: linux-leds@vger.kernel.org On Mon, 17 Aug 2015 23:08:23 +0200, Vincent Pelletier wrote: > How can I debug this further ? I made a bit of progress: disabling all but one cpu (...which, in this case, just means disabling the second core) makes the error messages go away, and blinking works fine. There is a lock taken in __request_region, and released around schedule() when muxed. I guess this means region request is just pushed into a queue when resource is busy, then scheduler is told to let whatever else available run. I have no idea if the lock should be taken before or after remove_wait_queue after schedule call. FWIW: # cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 55 model name : Intel(R) Celeron(R) CPU J1800 @ 2.41GHz stepping : 8 microcode : 0x811 cpu MHz : 2582.817 cache size : 1024 KB physical id : 0 siblings : 1 core id : 0 cpu cores : 1 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 11 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 movbe popcnt tsc_deadline_timer rdrand lahf_lm 3dnowprefetch ida arat epb dtherm tpr_shadow vnmi flexpriority ept vpid tsc_adjust smep erms bugs : bogomips : 4825.60 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management: I'm looking for some resource tracing mechanism, but haven't found one yet. I suspect that there is a driver I haven't identified yet which would allocate resources incorrectly (or in an incompatible way, at least). Regards, -- Vincent Pelletier