[PATCH] tty: serial: Work around warning backtrace in serial8250_set_defaults

[Guenter Roeck]

Commit 7c7e6c8924e7 ("tty: serial: handle HAS_IOPORT dependencies")
triggers warning backtraces on a number of platforms which don't support
IO ports.

WARNING: CPU: 0 PID: 0 at drivers/tty/serial/8250/8250_port.c:470 serial8250_set_defaults+0x148/0x1d8
Unsupported UART type 0

The problem is seen because serial8250_set_defaults() is called for
all members of the serial8250_ports[] array even if that array is
not initialized.

Work around the problem by only displaying the warning if the port
type is not 0 (UPIO_PORT) or if iobase is set for the port.

Fixes: 7c7e6c8924e7 ("tty: serial: handle HAS_IOPORT dependencies")
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_port.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 4d63d80e78a9..649e74e9b52f 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -467,7 +467,8 @@ static void set_io_from_upio(struct uart_port *p)
 		break;
 #endif
 	default:
-		WARN(1, "Unsupported UART type %x\n", p->iotype);
+		WARN(p->iotype != UPIO_PORT || p->iobase,
+		     "Unsupported UART type %x\n", p->iotype);
 		p->serial_in = no_serial_in;
 		p->serial_out = no_serial_out;
 	}
-- 
2.45.2