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`
--
Tim Crawford
System76
Kernel Engineer
tcrawf...@system76.com
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