Coreboot with multiple gpu - coreboot

25 Oct 2019


      Hi all,
In my current board (AMD Bettong) I have a GPU integrated in the SOC and is working ok.
Also has two PCI connectors and in one of this I've connected a NVidia graphic card.
Running a debian distribution with both GPUs connected to two monitors hangs the system with
coreboot and with the original amibios one. With amibios is possible to disable the onboard GPU then
the system works ok. With the coreboot I've tried to do the same using the next code in OemCustomize.c
'OemPostParams()' method with no luck (Maybe this policy is not compiled in the Agesa black-box):
// Disable iGPU if any PCIe/PCI graphics card present.
    PostParams->GnbPostConfig.IgpuEnableDisablePolicy = IGPU_DISABLE_ANY_PCIE; ///< Disable iGPU if any PCI or PCIE graphics card is present
A more drastic approach is to disable the PCI related to the AMD onboard GPU in devicetree.cb
device pci 1.0 off end # Internal Graphics P2P bridge 0x9804
and set 'CONFIG_NO_GFX_INIT=y' to build the rom. Then, until grub menu I don't have any console.
Disabling the pci entry in devicetree.cb but with the GFX enabled I get the next error:
Timestamp - Option ROM initialization: 13568077860
CBFS @ 200 size 7ffe00
CBFS: 'Master Header Locator' located CBFS at [200:800000)
CBFS: Locating 'pci10de,1d01.rom'
CBFS: 'pci10de,1d01.rom' not found.
Option ROM address for PCI: 02:00.0 = f3000000
PCI expansion ROM, signature 0xaa55, INIT size 0xec00, data ptr 0x01a0
PCI ROM image, vendor ID 10de, device ID 1d01,
PCI ROM image, Class Code 030000, Code Type 00
Copying VGA ROM Image from f3000000 to 0xc0000, 0xec00 bytes
Timestamp - Option ROM copy done: 13719240943
Real mode stub @00000600: 889 bytes
Calling Option ROM...
... Option ROM returned.
VBE: Getting information about VESA mode 4122
VBE: Function call failed!
Error: In vbe_get_mode_info function
My questions:
 Is it possible to have the console redirected to the PCI graphic card?
 Is it possible to disable automatically the onboard GPU when a PCI graphic card is detected? Mainly don't relaying in Agesa code only coreboot PCI code...
Thanks!