From: John Ogness <john.ogness@linutronix.de>
To: Petr Mladek <pmladek@suse.com>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Jiri Slaby" <jirislaby@kernel.org>,
"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,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Tony Lindgren" <tony@atomide.com>,
"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Arnd Bergmann" <arnd@arndb.de>,
"Florian Fainelli" <florian.fainelli@broadcom.com>,
"Serge Semin" <fancer.lancer@gmail.com>,
"Wolfram Sang" <wsa+renesas@sang-engineering.com>,
"Lino Sanfilippo" <l.sanfilippo@kunbus.com>
Subject: Re: [PATCH next v2 3/4] serial: 8250: Switch to nbcon console
Date: Wed, 18 Sep 2024 17:25:05 +0206 [thread overview]
Message-ID: <84ed5hrnva.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <ZurG8YMmBmVVxttj@pathway.suse.cz>
On 2024-09-18, Petr Mladek <pmladek@suse.com> wrote:
> It would be fair to mention that it does not longer support fifo in
> the 8250 driver. It basically reverted the commit 8f3631f0f6eb42e5
> ("serial/8250: Use fifo in 8250 console driver").
Agreed.
> It is not usable in write_thread() because it would not allow
> a safe takeover between emitting particular characters.
If write_thread could exit_unsafe()/enter_unsafe() while busy-waiting,
then emergency/panic could still take over at any time. Even if it means
that atomic_write() would need to first wait for the FIFO to drain
(which it will). The important thing is that emergency/panic is able to
take over.
I dropped the optimization to keep things simple for now, but I agree
with Andy that it would be unfortunate. I will take a look at what such
an implementation could look like.
John
next prev parent reply other threads:[~2024-09-18 15:19 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-13 14:05 [PATCH next v2 0/4] convert 8250 to nbcon John Ogness
2024-09-13 14:05 ` [PATCH next v2 1/4] serial: 8250: Split out IER from rs485_start_tx() John Ogness
2024-09-17 14:48 ` Petr Mladek
2024-09-18 15:04 ` John Ogness
2024-09-19 15:01 ` Petr Mladek
2024-09-13 14:05 ` [PATCH next v2 2/4] serial: 8250: Split out IER from rs485_stop_tx() John Ogness
2024-09-14 10:18 ` kernel test robot
2024-09-18 9:53 ` Petr Mladek
2024-09-13 14:05 ` [PATCH next v2 3/4] serial: 8250: Switch to nbcon console John Ogness
2024-09-18 12:26 ` Petr Mladek
2024-09-18 14:01 ` Andy Shevchenko
2024-09-18 14:35 ` Petr Mladek
2024-09-18 17:03 ` Andy Shevchenko
2024-09-18 15:19 ` John Ogness [this message]
2024-09-18 14:47 ` John Ogness
2024-09-13 14:05 ` [PATCH next v2 4/4] serial: 8250: Revert "drop lockdep annotation from serial8250_clear_IER()" John Ogness
2024-09-18 12:52 ` Petr Mladek
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