serial: stm32: fix software flow control transfer

commit 037b91ec7729524107982e36ec4b40f9b174f7a2 upstream.

x_char is ignored by stm32_usart_start_tx() when xmit buffer is empty.

Fix start_tx condition to allow x_char to be sent.

Fixes: 48a6092fb4 ("serial: stm32-usart: Add STM32 USART Driver")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20220111164441.6178-3-valentin.caron@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Valentin Caron 2022-01-11 17:44:41 +01:00 committed by Greg Kroah-Hartman
parent 0b92eda2d8
commit 05b3301188

View File

@ -536,7 +536,7 @@ static void stm32_start_tx(struct uart_port *port)
{
struct circ_buf *xmit = &port->state->xmit;
if (uart_circ_empty(xmit))
if (uart_circ_empty(xmit) && !port->x_char)
return;
stm32_transmit_chars(port);