Hi,
1. The PCI multi MSI support was recently added to mainline by Marc Zyngier
Commit de337ee30142 ("irqchip/gic-v2m: Add PCI Multi-MSI support")
The Juno DT change is not yet merged.
https://patchwork.kernel.org/patch/10205273/
2. It's 32 PPI + SPI Number = GIC interrupt number
In the above case 168 is GIC interrupt corresponding to SPI 136.
This query is already being handled via Arm's support case system.
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