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

[Tomasz Nowicki]

On 20.09.2016 15:08, Bjorn Helgaas wrote:
> On Tue, Sep 20, 2016 at 09:06:23AM +0200, Tomasz Nowicki wrote:
>> 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
>
> There's no reason to avoid revision 0.  The question is really what
> firmware is already in the field.  We need to accommodate that.  We don't
> want a situation where kernel version X only works with firmware version Y,
> but kernel version X+1 only works with firmware version Y+1.

Yes I agree. We have already deployed the firmware where:
pass2.x has MCFG revision 1
pass1.x has MCFG revision 2
so we need to stick to this.

Thanks,
Tomasz