Kyösti Mälkki has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/31950 )
Change subject: device/pciexp_device: Add set_subsystem() for pciexp device ......................................................................
Patch Set 2:
(1 comment)
https://review.coreboot.org/#/c/31950/2/src/include/device/pciexp.h File src/include/device/pciexp.h:
https://review.coreboot.org/#/c/31950/2/src/include/device/pciexp.h@6 PS2, Line 6: #define PCIE_SUBSYSTEM_VENDOR_ID 0x94
yes, subsystem programming register is eventually different between PCI and PCIE. […]
Please reference the PCIe specs for register 0x94.
I very much believe the case is Intel implemented register 0x2C as read-only, and you will not find any mentions of register 0x94 in either of PCI or PCIe specifications. PCI silicon vendors were once told anything above 0x80 (or even 0x40) is free "namespace" for vendors to use so standards committee at least should not have chosen any new "standard" register from the region 0x80 to 0xFF.