serial: altera: set RRDY flag also without irq

The UART can be operated without an irq. In this case a timer is setup
that regularily calls altera_uart_interrupt(). The receiving part
depends on pp->imr having the bit ALTERA_UART_STATUS_RRDY_MSK set,
otherwise altera_uart_rx_chars() is never called. So ensure that the bit
gets set (disguised as ALTERA_UART_CONTROL_RRDY_MSK) by not returning
early from altera_uart_startup() if port->irq is 0.

This doesn't affect the hardware as the ALTERA_UART_CONTROL_RRDY_MSK bit
isn't actually written to the control register.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c
index 4278437..0e487ce 100644 (file)
--- a/drivers/tty/serial/altera_uart.c
+++ b/drivers/tty/serial/altera_uart.c
@@ -321,20 +321,20 @@ static int altera_uart_startup(struct uart_port *port)
 {
        struct altera_uart *pp = container_of(port, struct altera_uart, port);
        unsigned long flags;
-       int ret;
 
        if (!port->irq) {
                timer_setup(&pp->tmr, altera_uart_timer, 0);
                mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
-               return 0;
-       }
-
-       ret = request_irq(port->irq, altera_uart_interrupt, 0,
-                       DRV_NAME, port);
-       if (ret) {
-               pr_err(DRV_NAME ": unable to attach Altera UART %d "
-                      "interrupt vector=%d\n", port->line, port->irq);
-               return ret;
+       } else {
+               int ret;
+
+               ret = request_irq(port->irq, altera_uart_interrupt, 0,
+                               DRV_NAME, port);
+               if (ret) {
+                       pr_err(DRV_NAME ": unable to attach Altera UART %d "
+                              "interrupt vector=%d\n", port->line, port->irq);
+                       return ret;
+               }
        }
 
        spin_lock_irqsave(&port->lock, flags);