>>Jonathan Sturges wrote:
>> Two additional questions about CS5530 IRQ steering:
>> 1) Comments from Uwe Hermann and Peter Stuge have indicated that it's
>> really better for the kernel to setup the steering registers. Why is this?
>> It sounds like the BIOS is a good place to set these. I assume that a
>> knowledgeable OS could change them if necessary? At the very least, it does
>> sound like we all agree that it's OK to have LB setup the steering until
>> Linux is fixed.
>>
>> 2) Question about irq_tables.c. Many of the CS5536 systems have a
>> write_pirq_routing_table() in irq_tables.c that sets the steering registers.
>> I'd like to be able to set the steering registers in CS5530 systems too,
>> but I'm not a software developer and I need some help. So in
>> src/mainboard/artecgroup/dbe61/irq_tables.c, you have:
>> /* Set up chipset IRQ steering. */
>> pciAddr = 0x80000000 | (CHIPSET_DEV_NUM << 11) | 0x5C;
>> chipset_irq_map = (PIRQD << 12 | PIRQC << 8 | PIRQB << 4 | PIRQA);
>> printk_debug("%s(%08X, %04X)\n", __FUNCTION__, pciAddr,
>> chipset_irq_map);
>> outl(pciAddr & ~3, 0xCF8);
>> outl(chipset_irq_map, 0xCFC);My main question with this block of code is
>> what the two outl() calls are for. It looks like pciAddr gets the address
>> of the 0x5c steering register, and chipset_irq_map sets the right bits to
>> set all 4 PIRQ lines. But I'd expect to see the chipset_irq_map written to
>> pciAddr.
>>
>> As an alternative, Kenji Noguchi used this code block to set the registers
>> in a CS5530 system he's working on (posted 5-May-2007):
>> device_t pdev;
>> //CS5530A
>> pdev = dev_find_slot(0, (0x12 << 3) + 0);
>> pci_write_config8(pdev, 0x5c, 0xab);
>> pci_write_config8(pdev, 0x5d, 0x09);
>>
>>
>> This block makes more sense to me. Obviously the register values could be
>> set by
>> #defines, but it looks simpler to me.
>>
>> Bottom line is, before I implement IRQ steering for my CS5530 system, I want
>> to understand what the first code block is doing, and if (or why) it's
>> preferable over the 2nd code block. Any guidance is appreciated.
>>
>> thanks,
>> Jonathan
>
>
>outl(pciAddr & ~3, 0xCF8);
>outl(chipset_irq_map, 0xCFC)
>
>is basically the same as
>
>pci_write_config8(pdev, 0x5c, 0xab);
>pci_write_config8(pdev, 0x5d, 0x09);
>
>
>CFC/CF8 is the PCI config space.
Ahhh... thanks Marc, that was the clarification I needed.
With that in mind, that block of code should work directly with the CS5530
after defining CHIPSET_DEV_NUM appropriately. What about '0x80000000', is that
a common base address applicable to all CS553x systems?
thanks,
Jonathan
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