1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/serial/pmac_zilog.c b/drivers/serial/pmac_zilog.c
index 0700cd10b97c..683e66f18e8c 100644
--- a/drivers/serial/pmac_zilog.c
+++ b/drivers/serial/pmac_zilog.c
@@ -411,6 +411,17 @@ static void pmz_transmit_chars(struct uart_pmac_port *uap)
                 goto ack_tx_int;
         }
 
+        /* Under some circumstances, we see interrupts reported for
+         * a closed channel. The interrupt mask in R1 is clear, but
+         * R3 still signals the interrupts and we see them when taking
+         * an interrupt for the other channel (this could be a qemu
+         * bug but since the ESCC doc doesn't specify precsiely whether
+         * R3 interrup status bits are masked by R1 interrupt enable
+         * bits, better safe than sorry). --BenH.
+         */
+        if (!ZS_IS_OPEN(uap))
+                goto ack_tx_int;
+
         if (uap->port.x_char) {
                 uap->flags |= PMACZILOG_FLAG_TX_ACTIVE;
                 write_zsdata(uap, uap->port.x_char);