Re: Geode GX1 and IRQ tables

[ramesh bios]

The URL for the Cox/Weinigel thread about PIRQ tables
on the geode gx1 is at:
http://lkml.org/lkml/2002/7/5/104

I'm doing a little bit more analysis of the problem
now. I've been looking at the following block of code
from 2.6.10's pci/irq.c. First of all, LB states this
during bootup:
---
Checking IRQ routing tables...
/bios/freebios/src/arch/i386/lib/pirq_routing.c:   
30:check_pirq_routing_table() - irq_routing_table
located at: 0x00008740
done.
Copying IRQ routing tables to 0xf0000...done.
Verifing priq routing tables copy at 0xf0000...failed
Wrote linuxbios table at: 00000500 - 00000664 
checksum f9fe
---
I'm not sure why the copy to 0xf0000 failed. That's
kinda odd but I'll live with it for now. Now, I put
some debug in the kernel code to see whether it found
the pirq table and I saw:

---
no pirq_table so calling pcibios_get_irq_routing_table
pirq_table=00000000
---

coming from pcibios_irq_init. So based on the code
appended below, I believe that the kernel isn't
finding the pirq table. And I think this is because
the kernel's pirq_find_routing_table function only
looks from __va(0xf0000) to __va(0x100000) whereas LB
puts it at 0000500. The second attempt that the kernel
makes to get the PIRQ table is with
pcibios_get_irq_routing_table and that fails too. I
need to look at that, but first I think I'll look into
why the copy to f0000 fails. In the meantime, any
advice?

---
static int __init pcibios_irq_init(void)
{
        DBG("PCI: IRQ init\n");

if (pcibios_enable_irq || raw_pci_ops == NULL)
                return 0;

dmi_check_system(pciirq_dmi_table);

pirq_table = pirq_find_routing_table();

#ifdef CONFIG_PCI_BIOS
        if (!pirq_table && (pci_probe &
PCI_BIOS_IRQ_SCAN)) {
                printk(KERN_WARNING "no pirq_table so
calling pcibios_get\n");
                pirq_table =
pcibios_get_irq_routing_table();
                printk(KERN_WARNING
"pirq_table=%p\n",pirq_table);
        }
#endif
        if (pirq_table) {
                printk(KERN_WARNING "had
pirq_table\n");
                pirq_peer_trick();
                pirq_find_router(&pirq_router);
                if (pirq_table->exclusive_irqs) {
                        int i;
                        for (i=0; i<16; i++)
                                if
(!(pirq_table->exclusive_irqs & (1 << i)))

pirq_penalty[i] += 100;
                }
                /* If we're using the I/O APIC, avoid
using the PCI IRQ routing table */
                if (io_apic_assign_pci_irqs) {
                        printk(KERN_WARNING "using
io_apic to assign irqs\n");
                        pirq_table = NULL;
                }
        }

pcibios_enable_irq = pirq_enable_irq;

pcibios_fixup_irqs();
        return 0;
}
---

--- "Ronald G. Minnich"  wrote:
> On Tue, 1 Mar 2005, Richard Smith wrote:
> > I've found that Linux up to 2.6.9 (I haven't
>
> tested .10)  Dosen't do
> > this fully.  With my 440bx chipset there are
>
> config registers in the
> > northbridge that control which IRQ line each of
>
> the PCI PIRQ lines are
> > routed to.  Even with a proper PIRQ table these
>
> registers are not setup
> > and I get the same error reported.
>
> that's whacky. The old linux did fine with 440bx. I
> never had to do 
> anything but set up PIRQ tables.
> > I suggest you diff the output of lspci -xxx for
>
> the northbridge between
> > linubios and factory bios and resolve all the
>
> differences with the
> > datasheet.
>
> on the geode 2.4.18 always worked, and if I patched
> linux for later 
> linuxes, that worked fine too.
>
> What a mess PIRQ got to be ....
>
> ron

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com