Re: [PATCH V6 4/5] PCI: thunder: Enable ACPI PCI controller for ThunderX pass2.x silicon version

[Tomasz Nowicki]

On 19.09.2016 17:45, Bjorn Helgaas wrote:
> On Fri, Sep 09, 2016 at 09:24:06PM +0200, Tomasz Nowicki wrote:
> > ThunderX PCIe controller to off-chip devices (so-called PEM) is not fully
> > compliant with ECAM standard. It uses non-standard configuration space
> > accessors (see pci_thunder_pem_ops) and custom configuration space granulation
> > (see bus_shift = 24). In order to access configuration space and
> > probe PEM as ACPI based PCI host controller we need to add MCFG quirk
> > infrastructure. This involves:
> > 1. Export PEM pci_thunder_pem_ops structure so it is visible to MCFG quirk
> >    code.
> > 2. New quirk entries for each PEM segment. Each contains platform IDs,
> >    mentioned pci_thunder_pem_ops and CFG resources.
> >
> > Quirk is considered for ThunderX silicon pass2.x only which is identified
> > via MCFG revision 1.
>
> Is it really the case that silicon pass2.x has MCFG revision 1, and
> silicon pass1.x has MCFG revision 2?  That just seems backwards.

It is weird but silicon pass2.x is more common and it had MCFG revision 
1 from the beginning. Unless it is allowed to use MCFG revision 0 ? Then 
we could use MCFG revision 0 for pass1.x

Tomasz