It is possible that RX TIMEOUT is signalled after RX FIFO has been
drained, in which case a dummy read of RX FIFO is required to clear RX
TIMEOUT condition. Otherwise, RX TIMEOUT condition is not cleared
leading to an interrupt storm
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx>
---
drivers/tty/serial/8250/8250_omap.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 8ac11eaeca51..c71bd766fa56 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -104,6 +104,9 @@
#define UART_OMAP_EFR2 0x23
#define UART_OMAP_EFR2_TIMEOUT_BEHAVE BIT(6)
+/* RX FIFO occupancy indicator */
+#define UART_OMAP_RX_LVL 0x64
+
struct omap8250_priv {
int line;
u8 habit;
@@ -625,6 +628,15 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id)
serial8250_rpm_get(up);
iir = serial_port_in(port, UART_IIR);
ret = serial8250_handle_irq(port, iir);
+ /*
+ * It is possible that RX TIMEOUT is signalled after FIFO
+ * has been drained, in which case a dummy read of RX FIFO is
+ * required to clear RX TIMEOUT condition.
+ */
+ if ((iir & UART_IIR_RX_TIMEOUT) == UART_IIR_RX_TIMEOUT) {
+ if (serial_port_in(port, UART_OMAP_RX_LVL) == 0)
+ serial_port_in(port, UART_RX);
+ }
serial8250_rpm_put(up);
return IRQ_RETVAL(ret);
--
2.31.1
