Re: [PATCH 6/8] printk: Do not set Braille console as preferred_console

[John Ogness]

On 2026-02-19, Petr Mladek <pmladek@xxxxxxxx> wrote:
> We actually also need to prevent setting "preferred_dev_console" when
> the same console has been preferred as Braille before, for example:
>
>        console=brl,ttyS0,115200 console=ttyS0,115200
>
> One might argue that the later definition should win. But it would
> be a regression.
>
> The motivation to keep the current behavior is that the Braille console
> is special. IMHO, it should always win. Otherwise, the user might have
> hard times to debug the problem.

I have no experience about how a Braille console is used/configured in
the real world. But your reasoning is clear. Once a device has been
flagged as a Braille device, it can never be un-flagged.

> My new version of this code is:
>
> 	/*
> 	 * The last preferred console should get associated with /dev/console.
> 	 * Except for the Braille console which can't get associated with
> 	 * /dev/console. One level history should be enough because only one,
> 	 * the VisioBraille device, is supported at the moment.
> 	 */
> 	if (brl_options) {
> 		want_braille_console = true;
> 		if (preferred_dev_console == i) {
> 			preferred_dev_console = preferred_dev_console_prev;
> 			preferred_dev_console_prev = -1;
> 		}
> 	} else if (!is_braille_console_preferred(pc)) {
> 		preferred_dev_console_prev = preferred_dev_console;
> 		preferred_dev_console = i;
> 	}

Yes, this looks good. Thanks.

John