[U-Boot] [u-boot-release] [RFC PATCH 17/17] ns16550: wait for TENT before initializing

[Timur Tabi]

Scott Wood wrote:
> This prevents output problems (including a loss of synchronization
> observed on p2020 that persisted for quite a while) if SPL has output
> still on its way out.  I'm not sure why this is only now beginning to
> happen, though.

The subject line says "TENT", but the macro says "TEMT".

Also, it would be nice to see a description of this bit somewhere.

> 
> Signed-off-by: Scott Wood <scottwood at freescale.com>
> ---
>  drivers/serial/ns16550.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
> index 0c23955..66201b6 100644
> --- a/drivers/serial/ns16550.c
> +++ b/drivers/serial/ns16550.c
> @@ -36,6 +36,9 @@
>  
>  void NS16550_init(NS16550_t com_port, int baud_divisor)
>  {
> +	while (!(serial_in(&com_port->lsr) & UART_LSR_TEMT))
> +		;
> +
>  	serial_out(CONFIG_SYS_NS16550_IER, &com_port->ier);
>  #if (defined(CONFIG_OMAP) && !defined(CONFIG_OMAP3_ZOOM2)) || \
>  					defined(CONFIG_AM33XX)


-- 
Timur Tabi
Linux kernel developer at Freescale