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Date:   Tue, 28 May 2019 20:04:47 +0200
From:   =?utf-8?Q?Ond=C5=99ej?= Jirman <megous@megous.com>
To:     =?utf-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Maxime Ripard <maxime.ripard@bootlin.com>,
        Chen-Yu Tsai <wens@csie.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-sunxi <linux-sunxi@googlegroups.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-media@vger.kernel.org
Subject: Re: [linux-sunxi] Re: [PATCH v2 00/10] Allwinner A64/H6 IR support
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Hello Clément,

On Tue, May 28, 2019 at 06:21:19PM +0200, Clément Péron wrote:
> Hi Ondřej,
> 
> On Mon, 27 May 2019 at 21:53, 'Ondřej Jirman' via linux-sunxi
> <linux-sunxi@googlegroups.com> wrote:
> >
> > Hi Clément,
> >
> > On Mon, May 27, 2019 at 09:30:16PM +0200, verejna wrote:
> > > Hi Clément,
> > >
> > > On Mon, May 27, 2019 at 08:49:59PM +0200, Clément Péron wrote:
> > > > Hi Ondrej,
> > > >
> > > > >
> > > > > I'm testing on Orange Pi 3.
> > > > >
> > > > > With your patches, I get kernel lockup after ~1 minute of use (ssh stops
> > > > > responding/serial console stops responding). I don't have RC controller to test
> > > > > the CIR. But just enabling the CIR causes kernel to hang shortly after boot.
> > > > >
> > > > > I tried booting multiple times. Other results:
> > > > >
> > > > > boot 2:
> > > > >
> > > > > - ssh hangs even before connecting (ethernet crashes/is reset)
> > > > >
> > > > > INFO: rcu_sched detected stalls on CPUs/tasks:
> > > > > rcu:    0-....: (1 GPs behind) idle=64a/0/0x3 softirq=4091/4091 fqs=2437
> > > > > dwmac-sun8i 5020000.ethernet eth0: Reset adapter.
> > > > > rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-... } 5696 jiffies s: 81 root: 0x1/.
> > > > > rcu: blocking rcu_node structures:
> > > > >  rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
> > > > > rcu:    0-....: (1 GPs behind) idle=64a/0/0x3 softirq=4091/4091 fqs=9714
> > > > > rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-... } 21568 jiffies s: 81 root: 0x1/.
> > > > > rcu: blocking rcu_node structures:
> > > > > rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
> > > > > rcu:    0-....: (1 GPs behind) idle=64a/0/0x3 softirq=4091/4091 fqs=17203
> > > > >
> > > > > above messages appear regularly.
> > > > >
> > > > > boot 3:
> > > > >
> > > > > rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
> > > > > rcu:    0-....: (9 GPs behind) idle=992/0/0x3 softirq=6123/6123 fqs=2600
> > > > >
> > > > >
> > > > > Sometimes serial console keeps working. Sometimes it locks up too (but not
> > > > > frequently). Storage locks up always (any program that was not run before
> > > > > the crash can't be started and lock up the kernel hard, programs that
> > > > > were executed prior, can be run again).
> > > > >
> > > > >
> > > > > Exactly the same kernel build on H5 seems to work (or at least I was not able to
> > > > > trigger the crash). So this seems to be limited to H6 for now.
> > > > >
> > > > > I suspect that the crash occurs sooner if I vary the light (turn on/off the table
> > > > > lamp light).
> > > > >
> > > > > Without your patches, everything works fine on H6, and I never see
> > > > > crashes/lockups.
> > > > >
> > > > > I tired physically covering the IR receiver, and that helps preventing the
> > > > > crash. As soon as I uncover it, the crash happens again in 1s or so:
> > > > >
> > > > > rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
> > > > > rcu:    0-....: (1 GPs behind) idle=4ea/0/0x3 softirq=4483/4484 fqs=2444
> > > > > rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
> > > > > rcu:    0-....: (1 GPs behind) idle=4ea/0/0x3 softirq=4483/4484 fqs=9777
> > > > >
> > > > > This time I got the hung task and reboot: (probably not directly related)
> > > > >
> > > > > INFO: task find:560 blocked for more than 120 seconds.
> > > > >       Not tainted 5.2.0-rc2+ #7
> > > > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > > > > find            D    0   560    551 0x00000000
> > > > > Call trace:
> > > > >  __switch_to+0x6c/0x90
> > > > >  __schedule+0x1f4/0x578
> > > > >  schedule+0x28/0xa8
> > > > >  io_schedule+0x18/0x38
> > > > >  __lock_page+0x12c/0x208
> > > > >  pagecache_get_page+0x238/0x2e8
> > > > >  __get_node_page+0x6c/0x310
> > > > >  f2fs_get_node_page+0x14/0x20
> > > > >  f2fs_iget+0x70/0xc60
> > > > >  f2fs_lookup+0xcc/0x218
> > > > >  __lookup_slow+0x78/0x160
> > > > >  lookup_slow+0x3c/0x60
> > > > >  walk_component+0x1e4/0x2e0
> > > > >  path_lookupat.isra.13+0x5c/0x1e0
> > > > >  filename_lookup.part.23+0x6c/0xe8
> > > > >  user_path_at_empty+0x4c/0x60
> > > > >  vfs_statx+0x78/0xd8
> > > > >  __se_sys_newfstatat+0x24/0x48
> > > > >  __arm64_sys_newfstatat+0x18/0x20
> > > > >  el0_svc_handler+0x9c/0x170
> > > > >  el0_svc+0x8/0xc
> > > > > Kernel panic - not syncing: hung_task: blocked tasks
> > > > > CPU: 1 PID: 34 Comm: khungtaskd Not tainted 5.2.0-rc2+ #7
> > > > > Hardware name: OrangePi 3 (DT)
> > > > > Call trace:
> > > > >  dump_backtrace+0x0/0xf8
> > > > >  show_stack+0x14/0x20
> > > > >  dump_stack+0xa8/0xcc
> > > > >  panic+0x124/0x2dc
> > > > >  proc_dohung_task_timeout_secs+0x0/0x40
> > > > >  kthread+0x120/0x128
> > > > >  ret_from_fork+0x10/0x18
> > > > > SMP: stopping secondary CPUs
> > > > > Kernel Offset: disabled
> > > > > CPU features: 0x0002,20002000
> > > > > Memory Limit: none
> > > > > Rebooting in 3 seconds..
> > > > >
> > > > >
> > > > > Meanwhile H5 based board now runs for 15 minutes without issues.
> > > > >
> > > > > So to sum up:
> > > > >
> > > > > - these crashes are definitely H6 IR related
> > > > >   - the same kernel, on H5 works
> > > > >   - covering the sensor prevents the crashes on H6
> > > > >
> > > > > So we should probably hold on with the series, until this is figured out.
> > > >
> > > > Thanks for testing, but I think it's more hardware related.
> > > > It seems that your IR is flooded or misconfigured for your board.
> > > > Could you add a simple print in the "sunxi_ir_irq"
> > >
> > > Yes, I get flood of IRQs with status = 0x30. (after I turn on the lamp,
> > > but it persists even after I turn it off and cover the IR sensor).
> >
> > Interestingly, status also contains RAC, and it's 0 in this case. So the
> > interrupt if firing with "No available data in RX FIFO" repeatedly. Regardless
> > of input.
> >
> > So there's something else up.
> 
> Really weird indeed...
> 
> I have pushed a new version, where I didn't enabled the support for
> others H6 board and the cover letter include a link to this thread.
> 
> It would be great if other sunxi users could test this series, to
> check if this issue in present in other OPi3 / Pine H64.

I don't know if this is enough. I'd rather prefer if the driver has a way
of detecting this situation and shutting the module down, at the very least,
instead of taking down the entire system with IRQ flood.

It may be detectable by checking RAC == 0 when RX FIFO available interrupt
flag is set.

Otherwise, this will eventually be forgotten (cover letters are not even stored
in git), and someone will fall into the trap again, after enabling r_ir on
their board, and end up chasing their tail for a day. I've initially only found
this is IR driver issue after a long unpleasant debugging session, chasing other
more obvious ideas (as when this happens there's absolutely nothing in the log
indicating this is IR issue).

regards,
	o.

> Regards,
> Clément
> >
> > regards,
> >         o.
> >
> > > That's weird, because on H6 in CIR_RXSTA, bit 5 is undefined but corresponding
> > > bit in CIR_RXINT is DRQ_EN (RX FIFO DMA Enable)
> > >
> > > So I'm not sure what it could be flooded with and why IRQs keep being
> > > fired, even with no sensor input after the FIFO is read.
> > >
> > > regards,
> > >       o.
> > >
> > > > If it's confirmed, maybe tweak the threshold configuration or
> > > > implement the new active_threshold will help.
> > > >
> > > > With my hardware Beelink GS1 and on Jernej's board (A64) there is no issue.
> > > >
> > > > I will disable all the other H6 boards until someone test it.
> > > >
> > > > Regards,
> > > > Clément
> > >
> > > _______________________________________________
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> >
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