[PATCH v4 1/2] serial: mxc: Wait for TX completion before reset

[Fabio Estevam]

On Thu, Jan 12, 2023 at 2:19 PM Loic Poulain <loic.poulain at linaro.org> wrote:
>
> The u-boot console may show some corrupted characters when
> printing in board_init() due to reset or baudrate change
> of the UART (probe) before the TX FIFO has been completely
> drained.
>
> To fix this issue, and in case UART is still running, we now
> try to flush the FIFO before proceeding to UART reinitialization.
> For this we're waiting for Transmitter Complete bit, indicating
> that the FIFO and the shift register are empty.
>
> flushing has a 4ms timeout guard, which is normally more than
> enough to consume the FIFO @ low baudrate (9600bps).
>
> Signed-off-by: Loic Poulain <loic.poulain at linaro.org>
> Tested-by: Lothar Waßmann <LW at KARO-electronics.de>

Reviewed-by: Fabio Estevam <festevam at denx.de>