bfin uart: it will hang when read current y count if not disable dma irq

Add irq disable and enable in bfin_serial_rx_dma_timeout in case of
system hang.

This reverts part of commit 9642dbe73c8a ("serial: bfin-uart: avoid
dead lock in rx irq handler in smp kernel").

Signed-off-by: Hao Liang <hliang1025@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/tty/serial/bfin_uart.c b/drivers/tty/serial/bfin_uart.c
index 43b3e2c233ff..155781ece050 100644
--- a/drivers/tty/serial/bfin_uart.c
+++ b/drivers/tty/serial/bfin_uart.c
@@ -464,6 +464,7 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
         int x_pos, pos;
         unsigned long flags;
 
+        dma_disable_irq_nosync(uart->rx_dma_channel);
         spin_lock_irqsave(&uart->rx_lock, flags);
 
         /* 2D DMA RX buffer ring is used. Because curr_y_count and
@@ -496,6 +497,7 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
         }
 
         spin_unlock_irqrestore(&uart->rx_lock, flags);
+        dma_enable_irq(uart->rx_dma_channel);
 
         mod_timer(&(uart->rx_dma_timer), jiffies + DMA_RX_FLUSH_JIFFIES);
 }