[PATCH 3.14 018/228] 8250_core: Fix unwanted TX chars write

[Greg Kroah-Hartman]

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Loic Poulain <loic.poulain@xxxxxxxxx>

commit b08c9c317e3f7764a91d522cd031639ba42b98cc upstream.

On transmit-hold-register empty, serial8250_tx_chars
should be called only if we don't use DMA.
DMA has its own tx cycle.

Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxx>
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/tty/serial/8250/8250_core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1520,7 +1520,7 @@ int serial8250_handle_irq(struct uart_po
 			status = serial8250_rx_chars(up, status);
 	}
 	serial8250_modem_status(up);
-	if (status & UART_LSR_THRE)
+	if (!up->dma && (status & UART_LSR_THRE))
 		serial8250_tx_chars(up);
 
 	spin_unlock_irqrestore(&port->lock, flags);


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