Messages in this thread | | | Subject | Re: [PATCH] coresight: dynamic-replicator: Fix handling of multiple connections | From | Suzuki K Poulose <> | Date | Mon, 27 Apr 2020 14:53:13 +0100 |
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On 04/27/2020 10:45 AM, Mike Leach wrote: > HI, > > On Mon, 27 Apr 2020 at 10:15, Suzuki K Poulose <suzuki.poulose@arm.com> wrote: >> >> On 04/26/2020 03:37 PM, Sai Prakash Ranjan wrote: >>> Since commit 30af4fb619e5 ("coresight: dynamic-replicator: >>> Handle multiple connections"), we do not make sure that >>> the other port is disabled when the dynamic replicator is >>> enabled. This is seen to cause the CPU hardlockup atleast >>> on SC7180 SoC with the following topology when enabling ETM >>> with ETR as the sink via sysfs. Since there is no trace id >>> logic in coresight yet to make use of multiple sinks in >>> parallel for different trace sessions, disable the other >>> port when one port is turned on. >>> >>> etm0_out >>> | >>> apss_funnel_in0 >>> | >>> apss_merge_funnel_in >>> | >>> funnel1_in4 >>> | >>> merge_funnel_in1 >>> | >>> swao_funnel_in >>> | >>> etf_in >>> | >>> swao_replicator_in >>> | >>> replicator_in >>> | >>> etr_in >>> >>> Kernel panic - not syncing: Watchdog detected hard LOCKUP on cpu 0 >>> CPU: 7 PID: 0 Comm: swapper/7 Tainted: G S B 5.4.25 #100 >>> Hardware name: Qualcomm Technologies, Inc. SC7180 IDP (DT) >>> Call trace: >>> dump_backtrace+0x0/0x188 >>> show_stack+0x20/0x2c >>> dump_stack+0xdc/0x144 >>> panic+0x168/0x370 >>> arch_seccomp_spec_mitigate+0x0/0x14 >>> watchdog_timer_fn+0x68/0x290 >>> __hrtimer_run_queues+0x264/0x498 >>> hrtimer_interrupt+0xf0/0x22c >>> arch_timer_handler_phys+0x40/0x50 >>> handle_percpu_devid_irq+0x8c/0x158 >>> __handle_domain_irq+0x84/0xc4 >>> gic_handle_irq+0x100/0x1c4 >>> el1_irq+0xbc/0x180 >>> arch_cpu_idle+0x3c/0x5c >>> default_idle_call+0x1c/0x38 >>> do_idle+0x100/0x280 >>> cpu_startup_entry+0x24/0x28 >>> secondary_start_kernel+0x15c/0x170 >>> SMP: stopping secondary CPUs >>> >>> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> >>> Tested-by: Stephen Boyd <swboyd@chromium.org>
>> >> This is not sufficient. You must prevent another session trying to >> enable the other port of the replicator as this could silently fail >> the "on-going" session. Not ideal. Fail the attempt to enable a port >> if the other port is active. You could track this in software and >> fail early. >> >> Suzuki > > While I have no issue in principle with not enabling a path to a sink > that is not in use - indeed in some cases attaching to unused sinks > can cause back-pressure that slows throughput (cf TPIU) - I am > concerned that this modification is masking an underlying issue with > the platform in question. > > Should we decide to enable the diversion of different IDs to different > sinks or allow different sessions go to different sinks, then this has > potential to fail on the SC7180 SoC - and it will be difficult in > future to associate a problem with this discussion.
Mike,
I think thats a good point. Sai, please could we narrow down this to the real problem and may be work around it for the "device" ? Do we know which sink is causing the back pressure ? We could then push the "work around" to the replicator it is connected to.
Suzuki
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