Hello,
I’m trying to find and fit all of the pieces together to get the display
running on my custom platform (based on Intel Comet Lake). Here are the
known facts...
1. The LCD including the backlight enable and PWM signals are all
connected to the eDP interface on the SoC.
2. When I booted the board using the regular AMI BIOS lspci reported:
00:02.0 VGA compatible controller [0300]: Intel Corporation Device
[8086:9bca] (rev 04) (prog-if 00 [VGA controller])
DeviceName: Onboard - Video
Subsystem: Device [1e50:800b]
3. I have managed to extract a VGA BIOS from the AMI BIOS file but the
PCIR structure lists Vendor ID: 0x8086, Device ID: 0x0406
4. I have also managed to extract a VBT binary from the AMI BIOS file
and have included it in the Coreboot image:
In the debug output when booting there are some VGA related messages:
POST: 0x73
found VGA at PCI: 00:02.0
Setting up VGA for PCI: 00:02.0
Setting PCI_BRIDGE_CTL_VGA for bridge DOMAIN: 0000
Setting PCI_BRIDGE_CTL_VGA for bridge Root Device
POST: 0x75
PCI: 00:02.0 init
FMAP: area COREBOOT found @ 490200 (11992576 bytes)
CBFS: Locating 'vbt.bin'
CBFS: 'vbt.bin' not found.
FMAP: area COREBOOT found @ 490200 (11992576 bytes)
CBFS: Locating 'pci8086,9b41.rom'
CBFS: 'pci8086,9b41.rom' not found.
PCI Option ROM loading disabled for PCI: 00:02.0
GMA: locate_vbt_vbios: c3e1 d591 6a 52 5f
GMA: VBT couldn't be found
Questions…
1. Why is the debug output claiming there is no vbt.bin file when it is
lised in the output at the end of the built (Size 1168 LZMA, 4608
decompressed)?
2. Why is it searching for pci8086,9b41.rom? I haven’t defined this and
the only reference I can see is in the system76/lemp9/Kconfig file?
3. Why doesn’t the VGA BIOS that I have extracted from the AMI BIOS file
match the PCI VID/DID of the VGA controller?
4. What else am I missing in order to get the screen to light up?
-Andy.
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