[PATCH 12/18] tty: serial: samsung: use TIOCSER_TEMT for tx_empty()

[Sam Protsenko]

On Wed, Jan 10, 2024 at 4:24 AM Tudor Ambarus <tudor.ambarus at linaro.org> wrote:
>
> The core expects for tx_empty() either TIOCSER_TEMT when the tx is
> empty or 0 otherwise. Respect the core and use TIOCSER_TEMT.
>
> Signed-off-by: Tudor Ambarus <tudor.ambarus at linaro.org>
> ---
>  drivers/tty/serial/samsung_tty.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index f2413da14b1d..46fba70f3d77 100644
> --- a/drivers/tty/serial/samsung_tty.c
> +++ b/drivers/tty/serial/samsung_tty.c
> @@ -990,11 +990,10 @@ static unsigned int s3c24xx_serial_tx_empty(struct uart_port *port)
>         if (ufcon & S3C2410_UFCON_FIFOMODE) {
>                 if ((ufstat & info->tx_fifomask) || (ufstat & info->tx_fifofull))
>                         return 0;
> -
> -               return 1;
> +               return TIOCSER_TEMT;
>         }
>
> -       return s3c24xx_serial_txempty_nofifo(port);
> +       return s3c24xx_serial_txempty_nofifo(port) ? TIOCSER_TEMT : 0;

And because s3c24xx_serial_txempty_nofifo() might actually return 0x4,
and at least uart_get_lsr_info() tries to clear exactly 0x1 bit, this
brings functional change, which I think is in fact a fix. So a
"Fixed:" tag is needed here.

>  }
>
>  /* no modem control lines */
> --
> 2.43.0.472.g3155946c3a-goog
>
>