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

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

[Luming Yu]

[-- Attachment #1: Type: text/plain, Size: 503 bytes --]

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(+)

[-- Attachment #2: 8250_pnp.patch --]
[-- Type: application/octet-stream, Size: 451 bytes --]

--- 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;

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

[Matthew Wilcox]

On Wed, Oct 17, 2007 at 10:50:53AM +0800, Luming Yu wrote:
> 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.

Seems reasonable to me.  Although arguably pnp_irq is broken, since
Linus has decreed that 0 means no irq on Linux.

-- 
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

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

[Alan Cox]

> Signed-off-by: Yu Luming <luming.yu@intel.com>
> 
>  8250_pnp.c |    3 +++
>  1 files changed, 3 insertions(+)

Should really fix pnp_irq() to use zero to mean none as the kernel
intends. If that causes other complications then this hack will do for
now I guess.

Alan