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@xxxxxxxxxxxxxx>
---
drivers/tty/serial/altera_uart.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/drivers/tty/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c
index 2ac4b80bfcd7..85d0ddc7108e 100644
--- a/drivers/tty/serial/altera_uart.c
+++ b/drivers/tty/serial/altera_uart.c
@@ -325,20 +325,20 @@ 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);
--
2.15.1
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