[coreboot] Fwd: HT chains fixup
mylesgw at gmail.com
Thu Nov 20 18:31:47 CET 2008
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
> > 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
> > 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.
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