[PATCH v2 5/6] serial: Call flush() before changing baudrate

[Simon Glass]

On Thu, 11 Aug 2022 at 06:39, Pali Rohár <pali at kernel.org> wrote:
>
> Changing baudrate is sensitive operation. To ensure that U-Boot messages

is a sensitive

> printed before changing baudrate are not lost, call new U-Boot console
> flush() function.
>
> Signed-off-by: Pali Rohár <pali at kernel.org>
> ---
>  cmd/load.c                     | 5 +++++
>  drivers/serial/serial-uclass.c | 1 +
>  drivers/serial/serial.c        | 1 +
>  3 files changed, 7 insertions(+)
>
> diff --git a/cmd/load.c b/cmd/load.c
> index e44ae0d56b75..5c4f34781d45 100644
> --- a/cmd/load.c
> +++ b/cmd/load.c
> @@ -83,6 +83,7 @@ static int do_load_serial(struct cmd_tbl *cmdtp, int flag, int argc,
>                 printf("## Switch baudrate to %d bps and press ENTER ...\n",
>                         load_baudrate);
>                 udelay(50000);
> +               flush();
>                 gd->baudrate = load_baudrate;
>                 serial_setbrg();
>                 udelay(50000);
> @@ -126,6 +127,7 @@ static int do_load_serial(struct cmd_tbl *cmdtp, int flag, int argc,
>                 printf("## Switch baudrate to %d bps and press ESC ...\n",
>                         current_baudrate);
>                 udelay(50000);
> +               flush();
>                 gd->baudrate = current_baudrate;
>                 serial_setbrg();
>                 udelay(50000);
> @@ -317,6 +319,7 @@ int do_save_serial(struct cmd_tbl *cmdtp, int flag, int argc,
>                 printf("## Switch baudrate to %d bps and press ESC ...\n",
>                         (int)current_baudrate);
>                 udelay(50000);
> +               flush();
>                 gd->baudrate = current_baudrate;
>                 serial_setbrg();
>                 udelay(50000);
> @@ -471,6 +474,7 @@ static int do_load_serial_bin(struct cmd_tbl *cmdtp, int flag, int argc,
>                 printf("## Switch baudrate to %d bps and press ENTER ...\n",
>                         load_baudrate);
>                 udelay(50000);
> +               flush();
>                 gd->baudrate = load_baudrate;
>                 serial_setbrg();
>                 udelay(50000);
> @@ -533,6 +537,7 @@ static int do_load_serial_bin(struct cmd_tbl *cmdtp, int flag, int argc,
>                 printf("## Switch baudrate to %d bps and press ESC ...\n",
>                         current_baudrate);
>                 udelay(50000);
> +               flush();
>                 gd->baudrate = current_baudrate;
>                 serial_setbrg();
>                 udelay(50000);
> diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
> index 4e32270d4660..0f6860d9100e 100644
> --- a/drivers/serial/serial-uclass.c
> +++ b/drivers/serial/serial-uclass.c
> @@ -527,6 +527,7 @@ static int on_baudrate(const char *name, const char *value, enum env_op op,
>                         printf("## Switch baudrate to %d bps and press ENTER ...\n",
>                                baudrate);
>                         udelay(50000);
> +                       flush();
>                 }
>
>                 gd->baudrate = baudrate;
> diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
> index 6cdbb89841c1..4b525b644928 100644
> --- a/drivers/serial/serial.c
> +++ b/drivers/serial/serial.c
> @@ -81,6 +81,7 @@ static int on_baudrate(const char *name, const char *value, enum env_op op,
>                         printf("## Switch baudrate to %d"
>                                 " bps and press ENTER ...\n", baudrate);
>                         udelay(50000);
> +                       flush();

Please don't implement new features in legacy code.

>                 }
>
>                 gd->baudrate = baudrate;
> --
> 2.20.1
>

Regards,
SImon