Re: [coreboot] v3 HT

[Myles Watson]

> -----Original Message-----
> From: Marc Jones [mailto:[e-mail]]
> Sent: Monday, October 27, 2008 3:26 PM
> To: Myles Watson
> Cc: 'ron minnich'; 'Coreboot'
> Subject: Re: [coreboot] v3 HT
>
> Myles Watson wrote:
> > > -----Original Message-----
> > > From: Marc Jones [mailto:[e-mail]]
> > > Sent: Monday, October 27, 2008 3:10 PM
> > > To: Myles Watson
> > > Cc: 'ron minnich'; 'Coreboot'
> > > Subject: Re: [coreboot] v3 HT
> > >
> > > Myles Watson wrote:
> > > > > -----Original Message-----
> > > > > From: ron minnich [mailto:[e-mail]]
> > > > > 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
> > >
> > > 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.
> > > > Find bridges and set them to not decode
> > > > Set first bridge to decode all device numbers (HT Unit IDs)
> > > > Do PCI scan on bridge with remaining non-bridge children
> > > > Find next bridge
> > > > Set to decode next device numbers
> > > > 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.
> >
> > So the collapse existing enumeration needs to be taken out?
>
> I didn't know that there was a collapse. That might not be good since a
> bridge could be "hard coded" to a location. That is ok if bus numbers
> are arbitrary. It they get colapsed that would be bad. I need to go
> understand this part of the dts/scan more.

It's not part of the dts.  It's also in v2 ht_collapse_early_enumeration.

Thanks,
Myles