PCI changes 2.6.26 => 2.6.28

[Gary Thomas]

Kumar Gala wrote:
> 
> On Apr 21, 2009, at 6:45 PM, Gary Thomas wrote:
> 
>> Kumar Gala wrote:
>>>
>>> On Apr 21, 2009, at 6:00 PM, Gary Thomas wrote:
>>>
>>>>
>>>> I found the difference - in 2.6.28 the inbound/outbound windows
>>>> don't seem to be set up at all.  In 2.6.26, the function
>>>> 'fsl_add_bridge'
>>>> was common among architectures and ended up calling 'setup_pci_atmu'
>>>> which created those mappings.  In 2.6.28, the 83xx PCI setup code
>>>> has been refactored.  It uses 'mpc83xx_add_bridge' instead of
>>>> 'fsl_add_bridge' and 'setup_pci_atmu' is not called at all :-(
>>>>
>>>> I'm sure this is the problem.
>>>
>>> Looking at a diff between 2.6.26 and .28 I don't see the 83xx pci code
>>> calling setup_pci_atmu().
>>
>> It did not directly; it called 'fsl_add_bridge' which in turn called
>> 'setup_pci_atmu'
> 
> Don't ever see 83xx boards calling fsl_add_bridge -- that is 85xx/86xx
> only in 83xx.

Sorry, you're correct.  I got lost looking through the code :-(
No matter, none of that code seems to be relevant to the change
in behaviour.

>> I modified the 2.6.28 driver to also call this function.  Now the
>> inbound/outbound windows are set up, but the bridge still has
>> no allocations, so the problem remains.
>>
>> I need to move on; I may just live with sliding the PCI space
>> up for now (doesn't really hurt anything, just seems like a hack)
> 
> It is and you are glossing over a real bug.

I have found the culprit - in arch/powerpc/kernel/pci_32.c

static void
fixup_hide_host_resource_fsl(struct pci_dev *dev)
{
	int i, class = dev->class >> 8;

#if 0
	if ((class == PCI_CLASS_PROCESSOR_POWERPC ||
	     class == PCI_CLASS_BRIDGE_OTHER) &&
#else
        if ((class == PCI_CLASS_PROCESSOR_POWERPC) &&
#endif
		(dev->hdr_type == PCI_HEADER_TYPE_NORMAL) &&
		(dev->bus->parent == NULL)) {
		for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
			dev->resource[i].start = 0;
			dev->resource[i].end = 0;
			dev->resource[i].flags = 0;
		}
	}
}
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_MOTOROLA, PCI_ANY_ID, fixup_hide_host_resource_fsl);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_FREESCALE, PCI_ANY_ID, fixup_hide_host_resource_fsl);

This function is now (the #if 0 case is in 2.6.28) tossing out
the memory resources used by the PCI bridge itself.  This makes
everything fall over, at least on my 834x platform.

This change was applied 2008-10-08, but it seems incorrect on the 834x.

> Are you using u-boot to boot?  If so is the board port public?

My systems use RedBoot (I'm the original author of RedBoot, so one would
expect that).  At this moment, the code isn't public, sorry.

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------
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