[coreboot] v3 HT

Marc Jones Marc.Jones at amd.com
Mon Oct 27 22:10:26 CET 2008

Myles Watson wrote:
>> -----Original Message-----
>> From: ron minnich [mailto:rminnich at gmail.com]
>> Sent: Monday, October 27, 2008 8:57 AM
>> To: Myles Watson
>> Cc: Coreboot
>> Subject: Re: [coreboot] v3 HT
>> On Mon, Oct 27, 2008 at 7:48 AM, Myles Watson <mylesgw at gmail.com> wrote:
>>> I don't think we need to expand the dts to fix this, we just need to
>> make
>>> the code match the structure.
>> Do you have a rough idea of how this would look in the code? This is a
>> good catch.
> Right now the code goes through the list of children and initializes them as
> bridges, without checking to see that they are.  Then it enumerates them
> with the pci code.
> I think we'd have to find the children that are bridges and then enumerate
> them with the list of children, so that we can pass parameters correctly.  I
> don't think it would be too hard.
> 1. Find bridges and set them to not decode 
> 2. Set first bridge to decode all device numbers (HT Unit IDs)
> 3. Do PCI scan on bridge with remaining non-bridge children
> 4. Find next bridge
> 5. Set to decode next device numbers
> 6. Goto 3

I think that the dts is can/should to handle arbitrary bus numbering 
(since a bridge can be plugged into any slot making everything change). 
The numbers are not so important if as long as the tree has the same 
connections (bridgeA has device 1, 2, 3 and bridgeB has x, y, z).

I don't think that you need a bridge scan before the device scan. It can 
be done as one. The device tree just needs to note the appropriate 
decode (bus number) for the bridge and the devices under it. Also, If 
the bus is already numbered we we shouldn't change it. Just use what is set.


Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones at amd.com

More information about the coreboot mailing list