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From: Philippe Gerum <rpm@xenomai.org>
To: Gabriel Durante <gabriel@neuraldsp.com>
Cc: xenomai@lists.linux.dev
Subject: Re: Xenomai 4 IMX8MM
Date: Thu, 04 Aug 2022 16:39:44 +0200
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Gabriel Durante <gabriel@neuraldsp.com> writes:

> Thanks Philippe,
>
> IRQCHIP_PIPELINE_SAFE flag on gpio-pca953x.c did the trick, no issues on dmesg.
>
> Now only the issue (kernel hangs) with edt_ft5x06 loaded while running
> sched-quota-accuracy.
>
> [ 2341.500412] edt_ft5x06 2-0038: Unable to fetch data, error: -110
>

I suspect this may be the outcome of the test overconsuming the CPU
bandwidth on the same processor which runs the (threaded?) IRQ handler
serving the touchpad events. IOW, the IRQ handler cannot run quickly
enough for the touchpad hw and/or driver to be happy, because
sched-quota-accuracy is keeping the CPU (too) busy.

Three options to check this:

- move the test away from CPU1, which might be shared with the IRQ
  handler, using the -c <cpu> option (you can run sched-quota-accuracy
  manually, outside of the 'evl test' scripting).

- change the CPU affinity of the IRQ for the touchpad device, away from
  CPU1. Fixing up /proc/irq/<irqnum>/smp_affinity accordingly may help,
  with <irqnum> matching the proper device in /proc/interrupts.

- try reducing the load imposed on the system by the test, e.g. by
  lowering the number of concurrent threads using the -n <nr_threads>
  option. Defaults to 3, maybe 1 would allow the test to pass in that
  configuration.

You also may want to make sure to switch off
CONFIG_PROVE_LOCKING->CONFIG_DEBUG_LOCK_ALLOC, CONFIG_DEBUG_LIST and
friends which slow down the (regular) kernel code a lot.

-- 
Philippe.