[coreboot] Fwd: HT chains fixup
marcj303 at gmail.com
Thu Nov 20 19:15:10 CET 2008
On Thu, Nov 20, 2008 at 10:31 AM, Myles Watson <mylesgw at gmail.com> wrote:
> On Thu, Nov 20, 2008 at 10:17 AM, Marc Jones <marcj303 at gmail.com> wrote:
>> On Wed, Nov 19, 2008 at 9:16 PM, Myles Watson <mylesgw at gmail.com> wrote:
>> >> What is gained by knowing the ht path?
>> > When a HT chain is powered on, all the devices have the same UnitID (0)
>> > The subordinate busses get assigned bus numbers in the order that they
>> > are
>> > found by PCI scan, but they are found in the order of the chain. As you
>> > assign each a device number, another device is visible at device 0 until
>> > the
>> > end of the chain is found.
>> Right, But I think that unitid setting happens before device scanning
>> and the dts is available. Once they are set there is no reason to
>> change them. The only thing is that the pci bridge code
> This is part of the confusing part. UnitIDs get set early so that the
> serial port works. I haven't gone through that code much yet, but it should
> only set up the southbridge link. That gets reset later when the chains are
> being enumerated with the dts. This is the "collapsing" we talked about in
> an earlier thread. In other words, when enumeration starts, all HT
> enumeration is blown away.
Sorry this got sent before I was done typing. I thought that the
collapse was also done in the early code as well.
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