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authorCheick Traore <cheick.traore@foss.st.com>2025-03-20 16:25:40 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2025-03-20 08:30:44 -0700
commit2790ce23951f0c497810c44ad60a126a59c8d84c (patch)
tree8676e82d75eca47425581fe65ca640f8f5d65f28
parent3d5390f4dbe633472b2a4824e66ca5c4eac6fb19 (diff)
serial: stm32: do not deassert RS485 RTS GPIO prematurely
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>
-rw-r--r--drivers/tty/serial/stm32-usart.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 4c97965ec43b..ad06b760cfca 100644
--- 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 uart_port *port)
{
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);