Re: [RESEND][PATCH 1/2] console: add new CONSOLE_ACTIVATE_ALL_FALLBACK option

[Sascha Hauer <s.hauer@pengutronix.de>]

On Fri, Jul 26, 2024 at 02:26:22PM +0200, Ahmad Fatoum wrote:
> We already have three CONSOLE_ACTIVATE options and every one of them has
> drawbacks:
> 
>   - ACTIVATE_ALL: May write barebox log to external devices like MCUs
>     that don't expect it
> 
>   - ACTIVATE_FIRST: Not applicable for most systems that probe from
>     device tree, where the order of probe is not necessarily fixed,
>     so what console is first may change over updates
> 
>   - ACTIVATE_NONE: has a misleading name and may leave the user without
>     any consoles at all if nothing else activates a console
> 
> Let's add a new option and make it the default, which avoids all these
> issues: Like ACTIVATE_NONE, it expects board code, DT or environment to
> enable a console and if none of them do it falls back to activating all
> consoles, so the user isn't kept in the dark with an error instructing
> the user to fix this.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
> Sent out second patch only by mistake instead of both...
> ---
>  common/Kconfig   | 19 ++++++++++++++++++-
>  common/console.c | 27 +++++++++++++++++++++++++++
>  2 files changed, 45 insertions(+), 1 deletion(-)
> 
> diff --git a/common/Kconfig b/common/Kconfig
> index 31360892aeef..2dda5ce5743a 100644
> --- a/common/Kconfig
> +++ b/common/Kconfig
> @@ -812,7 +812,7 @@ endchoice
>  choice
>  	prompt "Console activation strategy"
>  	depends on CONSOLE_FULL
> -	default CONSOLE_ACTIVATE_FIRST
> +	default CONSOLE_ACTIVATE_ALL_FALLBACK
>  
>  config CONSOLE_ACTIVATE_FIRST
>  	bool
> @@ -831,6 +831,23 @@ config CONSOLE_ACTIVATE_ALL
>  	  Only the first registered console will have the full startup
>  	  log though.
>  
> +config CONSOLE_ACTIVATE_ALL_FALLBACK
> +	bool
> +	prompt "activate all consoles as fallback"
> +	help
> +	  This option is similar to CONFIG_CONSOLE_ACTIVATE_NONE in that it
> +	  leaves consoles disabled on startup. If by the end of barebox
> +	  startup, no consoles have been activated via board code, device
> +	  tree or environment, barebox will enable all registered consoles
> +	  as fallback, so the user has a chance to see output.
> +
> +	  This will be indicated by a fat error, so the user knows that
> +	  the configuration needs to be fixed. If you don't see any
> +	  output at all, consider trying again after enabling
> +	  CONFIG_CONSOLE_ACTIVATE_ALL, so consoles are activated immediately
> +	  at registration time and/or with CONFIG_DEBUG_LL, so barebox output
> +	  is written even before console drivers were registered.
> +
>  config CONSOLE_ACTIVATE_NONE
>  	prompt "leave all consoles disabled"
>  	bool
> diff --git a/common/console.c b/common/console.c
> index 73b4c4d4db01..e83a3e1e2d7f 100644
> --- a/common/console.c
> +++ b/common/console.c
> @@ -450,6 +450,33 @@ int console_unregister(struct console_device *cdev)
>  }
>  EXPORT_SYMBOL(console_unregister);
>  
> +static int console_activate_all_fallback(void)
> +{
> +	int activate = CONSOLE_STDIOE;
> +	struct console_device *cdev;
> +
> +	for_each_console(cdev) {
> +		if (cdev->f_active & (CONSOLE_STDOUT | CONSOLE_STDERR))
> +			return 0;
> +	}
> +
> +	if (IS_ENABLED(CONFIG_CONSOLE_DISABLE_INPUT))
> +		activate &= ~CONSOLE_STDIN;
> +
> +	for_each_console(cdev)
> +		console_set_active(cdev, activate);
> +
> +	/*
> +	 * This is last resort, so the user is not kept in the dark.
> +	 * Writing to all consoles is a bad idea as the devices at the
> +	 * other side might get confused by it, thus the error log level.
> +	 */
> +	pr_err("No consoles were activated. Activating all consoles as fallback!\n");
> +
> +	return 0;
> +}
> +postenvironment_initcall(console_activate_all_fallback);

Shouldn't this code only run when CONSOLE_ACTIVATE_ALL_FALLBACK is
enabled?

Sascha

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