We have hit some blockers with porting Clevo ARL-HX boards that I'm hoping to get feedback about how to address.
1. PCIe devices for SoC and PCH are declared on separate buses.
- SoC: Devices on bus 0x00 - PCH: Devices on bus 0x80
There are conflicts between device/function that would prevent us from declaring them on the same bus. For example,
$ lspci -Dtvnn -s 14.0 -+-[0000:00]---14.0 Intel Corporation Device [8086:ae7f] <-- Shared SRAM (SOC-S) -[0000:80]---14.0 Intel Corporation Device [8086:7f6e] <-- USB 3.1 xHCI HC
We'd like to match this layout when porting new boards, but I don't think devicetree supports specifying the bus. And I don't know what else would need to change to handle it.
2. GPIO access for SoC and PCH are separate.
I have a lot less understanding about what's happening here and what's required.
One detail I got from Jeremy while he was trying to port a board was that this would impact ACPI/acpigen code:
the GPIOs in the first PCR region are from the CPU, and the PCH GPIOs are in another PCR region. I need to set the GPIOs for the PCH but none of the current coreboot code would work without specifying which PCR region to address.
Looking at the ACPI dump of a board, I see SoC and PCH devices are in separate regions.
- SoC: Uses `_SB.PC00` - PCH: Uses `_SB.PC02`
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Tim Crawford