serial: mpc52xx_uart: drop low-latency workaround

Commit fbe543b412ce ("Fix a potential issue in mpc52xx uart driver")
worked around the infamous low_latency behaviour of
tty_flip_buffer_push() by simply dropping and reacquiring the port lock
in the interrupt handler.

Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.

Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-16-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/mpc52xx_uart.c b/drivers/tty/serial/mpc52xx_uart.c
index af17004..2704dc9 100644 (file)
--- a/drivers/tty/serial/mpc52xx_uart.c
+++ b/drivers/tty/serial/mpc52xx_uart.c
@@ -1421,9 +1421,7 @@ mpc52xx_uart_int_rx_chars(struct uart_port *port)
                }
        }
 
-       spin_unlock(&port->lock);
        tty_flip_buffer_push(tport);
-       spin_lock(&port->lock);
 
        return psc_ops->raw_rx_rdy(port);
 }