Apollo Lake seems to start with PCIe root ports unusable/uninitialized
before FspMemoryInit() is called and FSP-M properly initializes these
root ports.
However, we need the root ports accessible before FspMemoryInit() in
certain cases, such as emitting POST codes through a PCIe device.
For the initialization to happen properly, certain register writes
specified in Apollo Lake IAFW BIOS spec, vol. 2 (#559811), chapter
3.3.1 have to be done.
BUG=none
TEST=Boot on siemens/mc_apl2 with NC_FPGA_POST_CODE enabled and check
that the POST codes are emitted before FspMemoryInit().
Change-Id: If782bfdd5f499dd47c085a0a16b4b15832bc040e
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Signed-off-by: Jan Samek <jan.samek@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68223
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
436f1c471a