From: Valentin Caron valentin.caron@foss.st.com
stable inclusion from stable-v5.10.96 commit 2683b0d5d7d549db9e48319135bade8ccb1adaa1 bugzilla: https://gitee.com/openeuler/kernel/issues/I55NWB
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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: 48a6092fb41f ("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 Signed-off-by: Yu Liao liaoyu15@huawei.com Reviewed-by: Wei Li liwei391@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- drivers/tty/serial/stm32-usart.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 844059861f9e..0eadf0547175 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -574,7 +574,7 @@ static void stm32_usart_start_tx(struct uart_port *port) struct serial_rs485 *rs485conf = &port->rs485; struct circ_buf *xmit = &port->state->xmit;
- if (uart_circ_empty(xmit)) + if (uart_circ_empty(xmit) && !port->x_char) return;
if (rs485conf->flags & SER_RS485_ENABLED) {