From: Chris Down <chris@chrisdown.name>
To: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Marcos Paulo de Souza <mpdesouza@suse.com>,
Naveen Kumar Chaudhary <naveen.osdev@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 13/16] printk: Try to register each console as Braille first
Date: Thu, 29 Oct 2026 15:17:42 +0800 [thread overview]
Message-ID: <auLzFtLAUEYKvXIO@chrisdown.name> (raw)
In-Reply-To: <20260929120546.328616-14-pmladek@suse.com>
Petr Mladek writes:
>Braille consoles are unique: they can only be enabled via the command
>line and use the preferred console framework for initialization, yet
>they are never added to the console_list or associated with
>/dev/console. Because of this, the preferred_console variable remains
>unset when only a Braille console is requested.
This also changes what happens when the same driver is wanted both ways, which
might be worth a sentence in the commit message.
For example:
console=ttyS1 console=brl,ttyS0
Here we used to end up with ttyS1 as a normal console and the Braille request
was silently ignored. Now ttyS0 becomes the Braille console, and every later
register_console() from serial core goes to the Braille round and gets -ENODEV
from braille_register_console(), so there is no serial console at all.
I think this is probably fine, but just needs clarifying in the commit message.
>+ * @try_only_braille and @user_specifified define which
-> @user_specified
>@@ -4033,6 +4061,24 @@ static int try_enable_console(struct console *newcon)
> {
> int err;
>
>+ /*
>+ * First, try to enable the console driver as a Braille console.
>+ * It would have metadata in the preferred_consoles[] array.
>+ * But it won't be counted as @preferred_console because
"@preferred_console" is preferred_dev_console now, and it is a variable rather
than a parameter, so no "@".
With those:
Acked-by: Chris Down <chris@chrisdown.name>
Thanks!
next prev parent reply other threads:[~2026-10-29 7:17 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-29 12:05 [PATCH v5 00/16] printk: Clean up preferred console handling Petr Mladek
2026-09-29 12:05 ` [PATCH v5 01/16] printk: Rename struct console_cmdline to preferred_console Petr Mladek
2026-10-29 7:03 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 02/16] printk: Rename preferred_console to preferred_dev_console Petr Mladek
2026-09-29 12:05 ` [PATCH v5 03/16] printk: Cleanup _braille_(un)register_console() wrappers Petr Mladek
2026-09-29 12:05 ` [PATCH v5 04/16] printk: Separate code for adding/updating preferred console metadata Petr Mladek
2026-10-27 12:05 ` John Ogness
2026-10-29 7:05 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 05/16] printk: Prefer the console either via name or devname exclusively Petr Mladek
2026-10-27 12:14 ` John Ogness
2026-10-29 7:06 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 06/16] printk: Check that index is not defined when a console is preferred via devname Petr Mladek
2026-10-27 18:08 ` John Ogness
2026-10-29 7:07 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 07/16] printk: Ensure consistent name and devname when updating preferred console Petr Mladek
2026-10-29 7:09 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 08/16] printk: Do not quietly ignore adding entry for a preferred console when there is no space Petr Mladek
2026-10-29 7:10 ` Chris Down
2026-10-29 16:23 ` John Ogness
2026-09-29 12:05 ` [PATCH v5 09/16] printk: Allow to override options via the command line Petr Mladek
2026-10-29 7:13 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 10/16] printk: Allow to debug misuse of add_or_update_preferred_console() Petr Mladek
2026-10-29 7:13 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 11/16] console/braille: Lock console->setup() call during the registration Petr Mladek
2026-10-29 7:15 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 12/16] printk: Separate code for enabling console Petr Mladek
2026-10-29 7:15 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 13/16] printk: Try to register each console as Braille first Petr Mladek
2026-10-29 7:17 ` Chris Down [this message]
2026-09-29 12:05 ` [PATCH v5 14/16] printk: Do not set Braille console as preferred_console Petr Mladek
2026-10-29 7:19 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 15/16] printk: Modify try_enable_default_console() to return error/success Petr Mladek
2026-10-29 7:20 ` Chris Down
2026-09-29 12:05 ` [PATCH v5 16/16] printk: Try enable preferred consoles only when there are any Petr Mladek
2026-10-29 7:20 ` Chris Down
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