[coreboot] AMG G-series - Steppe eagle - PCI IRQ Routing to 8259 PIC

[Abhishek Chaudhary]

Hi,

I am facing an issue routing the interrupts from the Ethernet devices which
are on GPP PCIe 1, GPP PCIe 2, and GPP PCIe 3 on a custom hardware that is
running AMD G-series - Steppe eagle (Mullins, Family 16h Model 30h-3Fh) .

I am attempting to use the PCI IRQ from the Ethernet devices, but this is
not working.  I am trying to route the PCI IRQ to legacy PIC using C00/C01
Interrupt Router.  I have verified the interrupt was generated by the
Ethernet end device but we don’t see it getting received by the PIC.

I am using FCH in PIC mode, and have local APIC and IOAPIC disabled.  In
this mode I am able to receive interrupts through PIC from Serial IRQ  and
 from 8254 timer on IRQ0. There are some limitations with the OS so i
cannot use IOAPIC, only legacy PIC can be used.

I do not have much experience with AMD platforms so i am sure what wrong i
am doing. Any input will be very helpful.

Thanks

Abhishek.