mb/prodrive/hermes: Allow using the Intel iGPU as primary

Configure the Intel iGPU as primary video adapter if enabled according
to EEPROM settings. The default is to use the ASPEED BMC as primary
video adapter, which only has a VGA output and the remote KVM output.

For now, use the FSP GOP driver to light up the iGPU. There are several
issues with libgfxinit on the Hermes, probably due to the unusual setup
of the iGPU's display outputs. They are routed to a mezzanine connector
for a piggy-back sub-board, of which there are two models. The Poseidon
piggy-back has two DisplayPort outputs and an HDMI output coming from a
MegaChips LSPCON. The Avalanche piggy-back routes all three DisplayPort
outputs from the iGPU into a FPGA, which acts as a DisplayPort sink.

Note that the FSP GOP only initializes at most 2 iGPU display outputs.
However, all three outputs function properly once OS (Windows, Linux)
graphics drivers take over.

Additionally, update the config file that Prodrive uses to build
coreboot images so that the iGPU can be used as primary.

TEST=Verify that the iGPU's outputs work properly in pre-OS, Windows and
     Linux, on both the Poseidon and Avalanche piggy-backs.

Change-Id: I24d9ebc2055dc246e7f257aa2f3853b22c8af370
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62649
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

0 files changed, 0 insertions, 0 deletions