[PATCH v11 09/14] irqchip/riscv-imsic: Add support for PCI MSI irqdomain

[Björn Töpel]

Thomas Gleixner <tglx at linutronix.de> writes:

> On Wed, Oct 25 2023 at 10:55, Björn Töpel wrote:
>>> Now for IMSIC-PCI domain, the PCI framework expects the
>>> pci_msi_mask/unmask_irq() functions to be called but if
>>> we directly point pci_msi_mask/unmask_irq() in the IMSIC-PCI
>>> irqchip then IMSIC-BASE (parent domain) irq_mask/umask
>>> won't be called hence the IRQ won't be masked/unmask.
>>> Due to this, we call both pci_msi_mask/unmask_irq() and
>>> irq_chip_mask/unmask_parent() for IMSIC-PCI domain.
>>
>> Ok. I wont dig more into it for now! If the interrupt is disabled at
>> PCI, it seems a bit overkill to *also* mask it at the IMSIC level...
>
> Only _if_ the device provides MSI masking, but that extra mask/unmask is
> not the end of the world.

Yikes -- so MSI masking is optional. Ick. :-( Thanks for the excellent
MSI vs MSI-X post in the other thread, BTW. Great stuff!