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From: Tony Lindgren <tony@atomide.com>
To: Romain Naour <romain.naour@smile.fr>
Cc: linux-omap@vger.kernel.org
Subject: Re: AM5749: tty serial 8250 omap driver crash
Date: Mon, 7 Feb 2022 10:04:31 +0200	[thread overview]
Message-ID: <YgDSj7FJS7nbkJol@atomide.com> (raw)
In-Reply-To: <2c80fd8a-2935-9a6d-43fd-f95fa53c93d2@smile.fr>

Hi,

* Romain Naour <romain.naour@smile.fr> [220204 13:39]:
> It seems that the driver fail to read the UART_LCR register from
> omap8250_set_mctrl():
> 
> "lcr = serial_in(up, UART_LCR);"
> 
> PC is at mem_serial_in+0x2c/0x30
> LR is at omap8250_set_mctrl+0x48/0xb0
> 
> The problem only occurs with a -rt kernel, I tried with several kernel version:
> 5.10-rt, 5.15-rt and 5.17-rt.
> 
> I'm not able to reproduce the issue with a standard kernel.

Interesting, what's the exception you get with the -rt kernel? Is it an
unhandled external abort or something else?

> While looking at the git history, I noticed this commit [3] about "flakey idling
> of uarts and stop using swsup_sidle_act".
> 
> So I removed the SYSC_QUIRK for uart IP revision 0x50411e03 and it fixed my issue.

Hmm.

> Is the SYSC_QUIRK for omap4 still needed ? Is it safe to remove it ?
> It seems this issue was introduced while dropping the legacy platform data
> (between 4.19 and 5.4 kernels).

AFAIK it's still needed, but maybe we can disable it for am57xx though.

Regards,

Tony

  reply	other threads:[~2022-02-07  8:23 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-04 13:39 AM5749: tty serial 8250 omap driver crash Romain Naour
2022-02-07  8:04 ` Tony Lindgren [this message]
2022-02-09  9:13   ` Romain Naour
2022-02-10 12:05     ` Tony Lindgren
2022-02-11 10:11       ` Romain Naour
2022-02-14  7:43         ` Tony Lindgren
2022-02-14 13:08           ` Tony Lindgren
2022-02-16  9:04             ` Romain Naour
2022-02-16 11:46               ` Tony Lindgren
2022-02-16 15:51                 ` Romain Naour
2022-02-17  8:08                   ` Tony Lindgren
2022-02-17  9:09                     ` Romain Naour
2022-02-17 12:58                       ` Tony Lindgren
2022-04-02 10:15                         ` Romain Naour
2022-05-03 10:05                           ` Tony Lindgren
2022-05-04 12:42                             ` Romain Naour
2022-05-05  4:33                               ` Tony Lindgren

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