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Date: Thu, 25 Jan 2024 14:35:23 +0100
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Chang, Junxiao" <junxiao.chang@intel.com>
Cc: John Ogness <john.ogness@linutronix.de>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"rostedt@goodmis.org" <rostedt@goodmis.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Li, Hao3" <hao3.li@intel.com>, "Li, Lili" <lili.li@intel.com>,
	"Gao, Jianfeng" <jianfeng.gao@intel.com>,
	"linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>
Subject: Re: RE: [PATCH 1/2] printk: nbcon: move locked_port flag to struct
 uart_port
Message-ID: <20240125133523.W7aDeBqt@linutronix.de>
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On 2024-01-25 01:08:24 [+0000], Chang, Junxiao wrote:
>=20
> Issue could be reproduced with our hardware every time. My cmdline is:
> BOOT_IMAGE=3D(hd0,gpt2)/boot/bzImage-linux-intel-iot-lts-rt-6.6-kernel
> root=3DPARTLABEL=3Dprimary rootwait console=3DttyS0,115200 console=3Dtty0
> init=3D/sbin/preinit-env console=3DttyS4,115200n8 console=3DttyS5,115200n8
>=20
> If you would like to try any debug patch with my ADL hardware, please fee=
l free to let me know.
>=20
> For console pointer sharing issue, from code logic point of view, the cal=
l chain looks like:
> serial8250_register_8250_port -> uart_add_one_port -> serial_ctrl_registe=
r_port -> serial_core_register_port -> serial_core_add_one_port
>=20
> In API serial_core_add_one_port, uart_port's console pointer is assigned =
with driver's console pointer:
> 	uport->cons =3D drv->cons;
> Driver's console pointer points to static structure "univ8250_console" wh=
ich is defined in 8250_core.c
>=20
> That is, all 8250 serial devices' console pointer are same, they point to=
 univ8250_console.

Okay, So that I see this and the unbalanced acquire/ release part with
the attached patch. I leave it to John=E2=80=A6
Btw. You don't see kernel log output on ttyS4 + ttyS5, right? Just a
login prompt.
=E2=80=A6
> Thanks,
> Junxiao

Sebastian