Irq 0 problem

Irq 0 problem

[Dayton, Dean]

I have been trying to port Linux 2.4.18-pre2 to the MPC8266ADS board. I
grabbed the SCC uart.c from 2.5.31.

The kernel loads and runs, the ramdisk is uncompressed and mounted. Then I
take an interrupt with SIVEC=0. SIVEC is now 0 everytime it is read, this
causes do_IRQ() to go into an endless loop.

I modified the code as follows:

 int do_IRQ()
 {
	...
	for (;;)
	{
		irq=get_irq()
-		if (irq >= 0)
+		if (irq > 0)
			ppc_irq_dispatch_handler()
		else
		...
	}
 }

This appears to solve (or at least hide) my problem. Has anyone else run
into this? I think it is occuring during the open of the console port (SCC
1). I ran into the same thing while trying to run on an EST8260 using an SMC
as the console. Am I simply covering up a problem with a misconfigured
device driver?

On another note, is anyone working on PCI support for an 8265/8266? That's
my next task.

Thanks
Dean
-------------
Dean Dayton
System Architect - Applied Innovation Inc.
(614)923-1174
deand@aiinet.com


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Re: Irq 0 problem

[Tom Rini]

On Fri, Sep 06, 2002 at 01:32:12PM -0400, Dayton, Dean wrote:

> I have been trying to port Linux 2.4.18-pre2 to the MPC8266ADS board. I
> grabbed the SCC uart.c from 2.5.31.

Why did you grab a file from 2.5.31?  And is there any reason you aren't
using 2.4.18 final or 2.4.19 final instead ?

> The kernel loads and runs, the ramdisk is uncompressed and mounted. Then I
> take an interrupt with SIVEC=0. SIVEC is now 0 everytime it is read, this
> causes do_IRQ() to go into an endless loop.
[snip]
> -		if (irq >= 0)
> +		if (irq > 0)
> 			ppc_irq_dispatch_handler()
[snip]
> This appears to solve (or at least hide) my problem. Has anyone else run
> into this? I think it is occuring during the open of the console port (SCC
> 1). I ran into the same thing while trying to run on an EST8260 using an SMC
> as the console. Am I simply covering up a problem with a misconfigured
> device driver?

I think the problem is you're using a kernel which doesn't have the 8260
irq function updated to return -1 when there's nothing pending..  Can
you verify that this is a problem with 2.4.19 or 2.4.18 ?

--
Tom Rini (TR1265)
http://gate.crashing.org/~trini/

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