[PATCH] tty/8250_pnp: serial port detection regression since v3.7

[Sean Young <sean@mess.org>]

The InsydeH2O BIOS (version dated 09/12/2011) has the following in
its pnp resouces for its serial ports:

$ cat /sys/bus/pnp/devices/00:0b/resources
state = active
io disabled
irq disabled

We do not check if the resources are disabled, and create a bogus
ttyS* device. Since commit 835d844d1a28e (8250_pnp: do pnp probe
before legacy probe) we get a bogus ttyS0, which prevents the legacy
probe from detecting it.

Reported-by: Vincent Deffontaines <vincent@gryzor.com>
Tested-by: Vincent Deffontaines <vincent@gryzor.com>
Signed-off-by: Sean Young <sean@mess.org>
Cc: stable@vger.kernel.org
---
 drivers/tty/serial/8250/8250_pnp.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_pnp.c b/drivers/tty/serial/8250/8250_pnp.c
index 35d9ab9..b3455a9 100644
--- a/drivers/tty/serial/8250/8250_pnp.c
+++ b/drivers/tty/serial/8250/8250_pnp.c
@@ -429,6 +429,7 @@ serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 {
 	struct uart_8250_port uart;
 	int ret, line, flags = dev_id->driver_data;
+	struct resource *res = NULL;
 
 	if (flags & UNKNOWN_DEV) {
 		ret = serial_pnp_guess_board(dev);
@@ -439,11 +440,12 @@ serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 	memset(&uart, 0, sizeof(uart));
 	if (pnp_irq_valid(dev, 0))
 		uart.port.irq = pnp_irq(dev, 0);
-	if ((flags & CIR_PORT) && pnp_port_valid(dev, 2)) {
-		uart.port.iobase = pnp_port_start(dev, 2);
-		uart.port.iotype = UPIO_PORT;
-	} else if (pnp_port_valid(dev, 0)) {
-		uart.port.iobase = pnp_port_start(dev, 0);
+	if ((flags & CIR_PORT) && pnp_port_valid(dev, 2))
+		res = pnp_get_resource(dev, IORESOURCE_IO, 2);
+	else if (pnp_port_valid(dev, 0))
+		res = pnp_get_resource(dev, IORESOURCE_IO, 0);
+	if (pnp_resource_enabled(res)) {
+		uart.port.iobase = res->start;
 		uart.port.iotype = UPIO_PORT;
 	} else if (pnp_mem_valid(dev, 0)) {
 		uart.port.mapbase = pnp_mem_start(dev, 0);
-- 
1.7.2.5