6.14-stable review patch. If anyone has any objections, please let me know.
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From: Cheick Traore cheick.traore@foss.st.com
commit 2790ce23951f0c497810c44ad60a126a59c8d84c upstream.
If stm32_usart_start_tx is called with an empty xmit buffer, RTS GPIO could be deasserted prematurely, as bytes in TX FIFO are still transmitting. So this patch remove rts disable when xmit buffer is empty.
Fixes: d7c76716169d ("serial: stm32: Use TC interrupt to deassert GPIO RTS in RS485 mode") Cc: stable stable@kernel.org Signed-off-by: Cheick Traore cheick.traore@foss.st.com Link: https://lore.kernel.org/r/20250320152540.709091-1-cheick.traore@foss.st.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/stm32-usart.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
--- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -965,10 +965,8 @@ static void stm32_usart_start_tx(struct { struct tty_port *tport = &port->state->port;
- if (kfifo_is_empty(&tport->xmit_fifo) && !port->x_char) { - stm32_usart_rs485_rts_disable(port); + if (kfifo_is_empty(&tport->xmit_fifo) && !port->x_char) return; - }
stm32_usart_rs485_rts_enable(port);