[U-Boot] [PATCH 13/69] x86: Allow use of serial soon after relocation

[Bin Meng]

Hi Simon,

On Mon, Mar 7, 2016 at 10:27 AM, Simon Glass <sjg at chromium.org> wrote:
> At present on x86 machines with use cache-as-RAM, the memory goes away just
> before board_init_r() is called. This means that serial drivers are
> no-longer unavailable, until initr_dm() it called, etc.
>
> Any attempt to use printf() within this period will cause a hang.
>
> To fix this, mark the serial devices as 'unavailable' when it is no-longer
> available. Bring it back when serial_initialize() is called. This means that
> the debug UART will be used instead for this period.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>  common/board_f.c               | 7 +++++++
>  drivers/serial/serial-uclass.c | 1 +
>  2 files changed, 8 insertions(+)
>
> diff --git a/common/board_f.c b/common/board_f.c
> index 622093a..109025a 100644
> --- a/common/board_f.c
> +++ b/common/board_f.c
> @@ -1096,6 +1096,13 @@ void board_init_f_r(void)
>                 hang();
>
>         /*
> +        * The pre-relocation drivers may be using memory that has now gone
> +        * away. Mark serial as unavailable - this will fall back to the debug
> +        * UART if available.
> +        */
> +       gd->flags &= ~GD_FLG_SERIAL_READY;
> +

What about other architectures (non-X86 and non-ARC)?

> +       /*
>          * U-Boot has been copied into SDRAM, the BSS has been cleared etc.
>          * Transfer execution from Flash to RAM by calculating the address
>          * of the in-RAM copy of board_init_r() and calling it
> diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
> index 1c447ff..6562be0 100644
> --- a/drivers/serial/serial-uclass.c
> +++ b/drivers/serial/serial-uclass.c
> @@ -116,6 +116,7 @@ int serial_init(void)
>  void serial_initialize(void)
>  {
>         serial_find_console_or_panic();
> +       gd->flags |= GD_FLG_SERIAL_READY;

I think we can simply replace this to:

void serial_initialize(void)
{
    serial_init();
}

Regards,
Bin