[RFC patch] fallback to "no irq" hack for case of no pnp_irq allocated for 8250_pnp

["Luming Yu" <luming.yu@gmail.com>]

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Hello list,

There is a "ttyS1 irq is -1" problem observed on tiger4 which cause
the serial port broken.
It is because that there is __no__ ACPI IRQ resource assigned for the
serial port. So the value of the IRQ for the port is never changed
since it got initialized to -1. The attached patch falls back to the
"no irq" hack for this case. It works for me. Please review and test.

Thanks,
Luming

Signed-off-by: Yu Luming <luming.yu@intel.com>

 8250_pnp.c |    3 +++
 1 files changed, 3 insertions(+)

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--- 2.6/drivers/serial/8250_pnp.c.orig	2007-10-16 14:18:19.000000000 +0800
+++ 2.6/drivers/serial/8250_pnp.c	2007-10-16 14:18:30.000000000 +0800
@@ -431,6 +431,9 @@
 
 	memset(&port, 0, sizeof(struct uart_port));
 	port.irq = pnp_irq(dev, 0);
+	/* No irq is assigned for the port, fallback to "no irq" hack */
+	if (port.irq == -1)
+		port.irq = 0; 
 	if (pnp_port_valid(dev, 0)) {
 		port.iobase = pnp_port_start(dev, 0);
 		port.iotype = UPIO_PORT;