On Thu, Feb 01, 2024 at 11:55 +0100, Jiri Slaby (SUSE) wrote:
> Emil reports:
> After updating Linux on an i.MX28 board, serial communication over
> AUART broke. When I TX from the board and measure on the TX pin, it
> seems like the HW fifo is not emptied before the transmission is
> stopped.
>
> MXS performs weird things with stop_tx(). The driver makes it
> conditional on uart_tx_stopped().
>
> So the driver needs special handling. Pass the brand new UART_TX_NOSTOP
> to uart_port_tx_flags() and handle the stop on its own.
>
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
> Reported-by: Emil Kronborg <emil.kronborg@xxxxxxxxxxxxxx>
> Fixes: 2d141e683e9a ("tty: serial: use uart_port_tx() helper")
> Closes: https://lore.kernel.org/all/miwgbnvy3hjpnricubg76ytpn7xoceehwahupy25bubbduu23s@om2lptpa26xw/
> ---
> drivers/tty/serial/mxs-auart.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> index 3ec725555bcc..4749331fe618 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -605,13 +605,16 @@ static void mxs_auart_tx_chars(struct mxs_auart_port *s)
> return;
> }
>
> - pending = uart_port_tx(&s->port, ch,
> + pending = uart_port_tx_flags(&s->port, ch, UART_TX_NOSTOP,
> !(mxs_read(s, REG_STAT) & AUART_STAT_TXFF),
> mxs_write(ch, s, REG_DATA));
> if (pending)
> mxs_set(AUART_INTR_TXIEN, s, REG_INTR);
> else
> mxs_clr(AUART_INTR_TXIEN, s, REG_INTR);
> +
> + if (uart_tx_stopped(&s->port))
> + mxs_auart_stop_tx(&s->port);
> }
>
> static void mxs_auart_rx_char(struct mxs_auart_port *s)
> --
> 2.43.0
>
Tested on i.MX28.
Tested-by: Emil Kronborg <emil.kronborg@xxxxxxxxxxxxxx>
--
Emil Kronborg
