8250_core: Fix unwanted TX chars write

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@intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index aa6db8f4ee187f5320bf0c1d32bf5d71596334f3..bf9d2ac9c9ed99514ae80b209e8f74f318fe15c2 100644 (file)
--- 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_port *port, unsigned int iir)
                        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);