[PATCH 4.19.y v2] serial: lantiq: add missing interrupt ack

[Bernhard Seibold <mail@xxxxxxxxxxxxxxxxxxx>]

commit 306320034e8fbe7ee1cc4f5269c55658b4612048 upstream.

Currently, the error interrupt is never acknowledged, so once active it
will stay active indefinitely, causing the handler to be called in an
infinite loop.

Fixes: 2f0fc4159a6a ("SERIAL: Lantiq: Add driver for MIPS Lantiq SOCs.")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Bernhard Seibold <mail@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Message-ID: <20230602133029.546-1-mail@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/tty/serial/lantiq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/lantiq.c b/drivers/tty/serial/lantiq.c
index 044128277248..c6b4bd67d4d9 100644
--- a/drivers/tty/serial/lantiq.c
+++ b/drivers/tty/serial/lantiq.c
@@ -251,6 +251,7 @@ lqasc_err_int(int irq, void *_port)
 	unsigned long flags;
 	struct uart_port *port = (struct uart_port *)_port;
 	spin_lock_irqsave(&ltq_asc_lock, flags);
+	ltq_w32(ASC_IRNCR_EIR, port->membase + LTQ_ASC_IRNCR);
 	/* clear any pending interrupts */
 	ltq_w32_mask(0, ASCWHBSTATE_CLRPE | ASCWHBSTATE_CLRFE |
 		ASCWHBSTATE_CLRROE, port->membase + LTQ_ASC_WHBSTATE);
-- 
2.41.0