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@vger.kernel.org Signed-off-by: Uwe Kleine-König u.kleine-koenig@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)