On Wed, Aug 08, 2018 at 11:49:46AM -0700, Ray Jui wrote: > > > On 8/8/2018 2:38 AM, Lorenzo Pieralisi wrote: > >On Tue, Aug 07, 2018 at 05:10:15PM -0700, Ray Jui wrote: > >>Hi Lorenzo/Bjorn, > >> > >>I have a question on PCIe controller APCI support on ARM64 based systems. > >> > >>If my understanding of the implementation of "pci_acpi_scan_root" under > >>"arch/arm64/kernel/pci.c" is correct, it appears > >>"pci_acpi_setup_ecam_mapping" is called within "pci_acpi_scan_root". > >> > >>Does that mean for a PCIe host controller on ARM64 to support ACPI, it needs > >>to support ECAM and MMIO based access to the configuration space registers? > >> > >>If the above statement is true, does it imply that any PCIe controller on > >>ARM64 that does not support MMIO based access to the config space register > >>cannot have ACPI support? > > > >Yes and it is not just MMIO, config space must be ECAM compliant as described > >in the PCI firmware specification and enforced here: > > > >http://infocenter.arm.com/help/topic/com.arm.doc.den0029b/Server_Base_System_Architecture_v5_0_ARM_DEN_0029B.pdf > > > > Okay, got it, the SBSA spec makes it very clear that the PCIe controller > needs to support ECAM. > > >In short: what's in the mainline (+ adequate PCI controller firmware > >configuration) must be sufficient to bootstrap your PCI subsystem in > >ACPI, it is a very simple litmus test and we won't add anything that > >deviates from that to the mainline kernel ARM64 ACPI PCI code support. > > > > It sounds like I'll have to look into ways to work around this at the driver > level as Bjorn pointed out with some other examples. As I said ARM64 ACPI PCI kernel support is in the mainline today and I am not willing to merge any more MCFG quirks at driver level - the information is out there, it is public and must be followed, either designers do that or no ACPI PCI support on your platform, sorry. Lorenzo
