[PATCH 2/2] serial: stm32: Reset .throttled state in .startup()

[Uwe Kleine-König]

When an UART is opened that still has .throttled set from a previous
open, the RX interrupt is enabled but the irq handler doesn't consider
it. This easily results in a stuck irq with the effect to occupy the CPU
in a tight loop.

So reset the throttle state in .startup() to ensure that RX irqs are
handled.

Fixes: d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode")
Cc: stable at vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
---
 drivers/tty/serial/stm32-usart.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 2bea1d7c9858..e1e7bc04c579 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -1080,6 +1080,7 @@ static int stm32_usart_startup(struct uart_port *port)
 		val |= USART_CR2_SWAP;
 		writel_relaxed(val, port->membase + ofs->cr2);
 	}
+	stm32_port->throttled = false;
 
 	/* RX FIFO Flush */
 	if (ofs->rqr != UNDEF_REG)
-- 
2.43.0