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From: John Ogness <john.ogness@linutronix.de>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Jiri Slaby" <jirislaby@kernel.org>,
	"Petr Mladek" <pmladek@suse.com>,
	"Sergey Senozhatsky" <senozhatsky@chromium.org>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Esben Haabendal" <esben@geanix.com>,
	linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Rengarajan S" <rengarajan.s@microchip.com>,
	"Niklas Schnelle" <schnelle@linux.ibm.com>,
	"Serge Semin" <fancer.lancer@gmail.com>,
	"Wander Lairson Costa" <wander@redhat.com>,
	"Florian Fainelli" <florian.fainelli@broadcom.com>,
	"Ray Jui" <rjui@broadcom.com>,
	"Scott Branden" <sbranden@broadcom.com>,
	"Broadcom internal kernel review list"
	<bcm-kernel-feedback-list@broadcom.com>,
	"Sunil V L" <sunilvl@ventanamicro.com>,
	"Matt Turner" <mattst88@gmail.com>,
	"Stefan Wahren" <wahrenst@gmx.net>,
	"Uwe Kleine-König" <u.kleine-koenig@baylibre.com>,
	"Kevin Hilman" <khilman@baylibre.com>,
	"Markus Schneider-Pargmann" <msp@baylibre.com>,
	"Udit Kumar" <u-kumar1@ti.com>,
	"Griffin Kroah-Hartman" <griffin@kroah.com>,
	linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	"Tony Lindgren" <tony@atomide.com>
Subject: Re: [PATCH tty-next v4 0/6] convert 8250 to nbcon
Date: Mon, 30 Dec 2024 12:06:29 +0106	[thread overview]
Message-ID: <841pxpqvua.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <Z3B5TQkz1S-C1wro@smile.fi.intel.com>

On 2024-12-29, Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> On Fri, Dec 27, 2024 at 11:51:16PM +0106, John Ogness wrote:
>> This is v4 of a series to convert the 8250 driver to an NBCON
>> console, providing both threaded and atomic printing
>> implementations. v3 of this series is here [0]. Additional
>> background information about NBCON consoles in general is
>> available in the cover letter of v2 [1].
>
> Just to be sure I understand the side effect of this series, i.e.
> the
>
> https://elixir.bootlin.com/linux/v6.13-rc3/source/drivers/tty/serial/8250/8250_port.c#L44
> https://elixir.bootlin.com/linux/v6.13-rc3/source/drivers/tty/serial/8250/8250_pci.c#L9
>
> are not needed anymore (the first one can be replaced to something like
> dev_dbg() or analogue)?

Correct. With NBCON console drivers it is safe to call printk() while
holding the port lock for non-console-printing purposes because:

1. printing via ->write_atomic() does not use the port lock

   and

2. printing via ->write_thread() is performed in a separate dedicated
   printing kthread that can safely spin on the port lock

John


  reply	other threads:[~2024-12-30 11:02 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-27 22:45 [PATCH tty-next v4 0/6] convert 8250 to nbcon John Ogness
2024-12-27 22:45 ` [PATCH tty-next v4 4/6] serial: 8250: Provide flag for IER toggling for RS485 John Ogness
2025-01-03 15:30   ` Petr Mladek
2025-01-05  0:26     ` John Ogness
2025-01-06 14:00       ` Petr Mladek
2024-12-28 22:18 ` [PATCH tty-next v4 0/6] convert 8250 to nbcon Andy Shevchenko
2024-12-30 11:00   ` John Ogness [this message]
2024-12-30 15:29 ` John Ogness

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