PCI on 834x

[Kumar Gala]

On Feb 24, 2010, at 4:14 PM, Gary Thomas wrote:

> On 02/24/2010 01:51 PM, Anton Vorontsov wrote:
>> On Wed, Feb 24, 2010 at 02:26:20PM -0600, Scott Wood wrote:
>>> Gary Thomas wrote:
>>>> Yes, I'm using the exact same kernel with these two different PCI
>>>> setups (done by the boot loader).
>>>> 
>>>> Restricting the memory via mem=128M has no effect - the PCI layout
>>>> is the same.
>>>> 
>>>> I think the outbound window size is required because of how the Linux PCI
>>>> remaps the space (note in my dumps that it put the MMIO of the
>>>> boards starting
>>>> at 0xD0000000 when the inbound window is 0x10000000)
>>> 
>>> I see where the amount of RAM is mattering -- Linux is assigning
>>> outbound I/O space to the PCI controller itself (device 00:00.0) and
>>> the amount that it asks for seems to differ based on memory size.
>>> Linux ought to skip that device when assigning resources.  Some
>>> platforms do this (search for pci_exclude_device), but it seems to
>>> be missing on 83xx.
>> 
>> Actually, 83xx had these exclude_device hooks, but they were removed:
>> 
>> commit d8f1324a5063c833862328ceafabc53ac3cc4f71
>> Author: Kumar Gala<galak at kernel.crashing.org>
>> Date:   Wed Sep 12 22:14:10 2007 -0500
>> 
>>     [POWERPC] 83xx: Removed PCI exclude of PHB
>> 
>>     Now that the generic code doesn't assign resources for Freescale
>>     PHBs we dont have to explicitly exclude it.
>> 
>>     Signed-off-by: Kumar Gala<galak at kernel.crashing.org>
>> 
>> 
>> May be the generic code started to assign the resources again?
>> 
> 
> That cracked it; I re-enabled the exclusion of the bridge and now
> it's all working fine.
> 
> Thanks for the help
> 
> Note: I'm working with a fairly old kernel, so these results would
> have to be reworked against the latest.

Odd that the generic code isn't dealing with that for you.

- k