From: Andre Renaud <arenaud@designa-electronics.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: kernel@pengutronix.de,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: iMX6/UART imprecise external abort
Date: Fri, 6 Dec 2019 08:29:40 +1300 [thread overview]
Message-ID: <CAEj2-1NPUyJ5WFM7hpQZmha=hmehuEOVppV_BQ4K6kcHUBnwpg@mail.gmail.com> (raw)
In-Reply-To: <20191202212948.c6dp7ifcvmjpwfhj@pengutronix.de>
On Tue, Dec 3, 2019 at 10:29 AM Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
> I saw a similar problem some time ago on a 4.14.69 and 4.19.72 with a
> backport of the UART driver from some newer release (around 5.4-rc1)
> plus some rs485 improvments and the -rt patch applied. I got some input
> by RMK on that and the situation is difficult. The address where the
> fault is reported to have happend doesn't say anything for an imprecise
> external abort.
>
> On our end the problem doesn't reproduce so easily up to now.
>
> I didn't come around to debug this problem, yet. I would do some
> shooting in the dark and start with:
>
> - disable DMA (doesn't help according to your report)
> - reproduce without -rt (still happens according to your report)
> - keep the UART clocks on. (Try removing
> "clk_disable_unprepare(sport->clk_ipg);" from imx_uart_probe())
Changing the clocking made the issue harder to reproduce, but it did
still occur eventually
> - try to reproduce in rs232 mode
> - try to record some traces of the problem
> (i.e. add tracing_off() to the fault handler and enable ftrace with a
> large enough trace buffer.)
We haven't tried these yet.
We did try fiddling with the IRQ affinity - we pushed the affinity for
the IRQ itself on to CPU 4 (ie: echo 8 > /proc/irq/67/smp_affinity),
and then we ran our test program on the same CPU with taskset (ie:
taskset 8 rs485_test).
Using this configuration I have not seen the issue reoccur on the
5.4.1 kernel, although the same settings do not resolve the issue on
our older 4.8 kernel.
Regards,
Andre
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next prev parent reply other threads:[~2019-12-05 19:30 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-02 20:40 iMX6/UART imprecise external abort Andre Renaud
2019-12-02 20:56 ` Fabio Estevam
2019-12-03 1:53 ` [EXT] " Andy Duan
2019-12-03 2:01 ` Andre Renaud
2019-12-03 2:06 ` Andy Duan
2019-12-03 2:28 ` Fabio Estevam
2019-12-03 6:24 ` Andre Renaud
2019-12-10 4:03 ` Andre Renaud
2019-12-10 5:46 ` [EXT] " Andy Duan
2019-12-10 22:07 ` Andre Renaud
2019-12-11 0:27 ` Fabio Estevam
2019-12-11 1:35 ` [EXT] " Andre Renaud
2019-12-11 1:59 ` Andre Renaud
2019-12-12 1:35 ` Fabio Estevam
2019-12-15 23:41 ` Andre Renaud
2019-12-02 21:29 ` Uwe Kleine-König
2019-12-05 19:29 ` Andre Renaud [this message]
2019-12-21 3:33 ` Andre Renaud
2019-12-21 7:31 ` [EXT] " Andy Duan
2019-12-21 12:03 ` Fabio Estevam
2019-12-23 1:53 ` Andy Duan
2019-12-23 10:16 ` Uwe Kleine-König
2020-01-07 22:24 ` Uwe Kleine-König
2020-01-08 1:43 ` Andy Duan
2020-01-08 4:03 ` Andre Renaud
2020-01-08 5:11 ` Andy Duan
2020-01-08 6:43 ` Uwe Kleine-König
2020-01-08 6:40 ` Uwe Kleine-König
2020-01-08 11:23 ` Uwe Kleine-König
2020-01-09 1:33 ` Andy Duan
2020-01-19 23:29 ` Andre Renaud
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