On 11/03/2016 10:00 AM, Bjorn Helgaas wrote:
It turns out that we can't use the _CRS of host bridges because of the Producer/Consumer bit screwup [1]. So the fallback is to include the ECAM space in the _CRS of a PNP0C02 device. This is what the PCI Firmware spec r3.0, Table 4-2, footnote 2 is talking about.
Bjorn
[1] The original ACPI spec intent was that Consumer resources would be space like ECAM that is consumed directly by the bridge, and Producer resources would be the windows forwarded down to PCI. But BIOSes didn't use the Producer/Consumer bit consistently, so we have to assume that all resources in host bridge _CRS are windows, which leaves us no way to describe the Consumer resources.
Aside - and now I realize you'd called this out as recently as last month. Alas the HPE m400 I reference on the other thread about the APM quirks doesn't have the motherboard resource entry so we're stuck with exactly the situation you describe above there.
Jon.