serial: bcm63xx_uart: fix irq storm after rx fifo overrun.

RX fifo reset is required to clear irq.

Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 14 insertions, 4 deletions

diff --git a/drivers/tty/serial/bcm63xx_uart.c b/drivers/tty/serial/bcm63xx_uart.c
index a1a0e55d0807..c0b68b9cad91 100644
--- a/drivers/tty/serial/bcm63xx_uart.c
+++ b/drivers/tty/serial/bcm63xx_uart.c
@@ -250,6 +250,20 @@ static void bcm_uart_do_rx(struct uart_port *port)
                 /* get overrun/fifo empty information from ier
                  * register */
                 iestat = bcm_uart_readl(port, UART_IR_REG);
+
+                if (unlikely(iestat & UART_IR_STAT(UART_IR_RXOVER))) {
+                        unsigned int val;
+
+                        /* fifo reset is required to clear
+                         * interrupt */
+                        val = bcm_uart_readl(port, UART_CTL_REG);
+                        val |= UART_CTL_RSTRXFIFO_MASK;
+                        bcm_uart_writel(port, val, UART_CTL_REG);
+
+                        port->icount.overrun++;
+                        tty_insert_flip_char(tty, 0, TTY_OVERRUN);
+                }
+
                 if (!(iestat & UART_IR_STAT(UART_IR_RXNOTEMPTY)))
                         break;
 
@@ -284,10 +298,6 @@ static void bcm_uart_do_rx(struct uart_port *port)
                 if (uart_handle_sysrq_char(port, c))
                         continue;
 
-                if (unlikely(iestat & UART_IR_STAT(UART_IR_RXOVER))) {
-                        port->icount.overrun++;
-                        tty_insert_flip_char(tty, 0, TTY_OVERRUN);
-                }
 
                 if ((cstat & port->ignore_status_mask) == 0)
                         tty_insert_flip_char(tty, c, flag);