[U-Boot] [PATCH v3] Add board_pre_console_putc to deal with early console output

[Graeme Russ]

Hi Simon,

On Wed, Oct 19, 2011 at 9:57 AM, Simon Glass <sjg at chromium.org> wrote:
> This patch adds support for console output before the console is inited.
> The main purpose of this is to deal with a very early panic() which would
> otherwise cause a silent hang.
>
> A new board_pre_console_putc() function is added to the board API. If
> provided by the board it will be called in the event of console output
> before the console is ready. This function should turn on all UARTs and
> spray the character out if it possibly can.
>
> The feature is controlled by a new CONFIG_PRE_CONSOLE_PUTC option.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---

[snip]

> diff --git a/common/console.c b/common/console.c
> index f17875e..d79bcf4 100644
> --- a/common/console.c
> +++ b/common/console.c
> @@ -329,14 +329,30 @@ int tstc(void)
>        return serial_tstc();
>  }
>
> -#ifdef CONFIG_PRE_CONSOLE_BUFFER
> +#ifdef CONFIG_PRE_CONSOLE_PUTC
> +/* Provide a default function for when no console is available */
> +static void __board_pre_console_putc(int ch)
> +{
> +       /* Just return since we can't access the console */
> +}
> +
> +void board_pre_console_putc(const char *msg) __attribute__((weak,
> +                                       alias("__board_pre_console_putc")));
> +#endif
> +
> +#if defined(CONFIG_PRE_CONSOLE_BUFFER) || defined(CONFIG_PRE_CONSOLE_PUTC)

I don't think we need this - If CONFIG_PRE_CONSOLE_PUTC then
board_pre_console_putc() must also be defined - I would prefer a
compilation due to undefined function that head-scratching as to why th
output I expected did not occur

[snip]

Regards,

Graeme