Re: [PATCH] [RFC] genirq/cpuhotplug, PCI/rcar-host: Silence set affinity failed warning

[Thomas Gleixner <tglx@linutronix.de>]

Marek!

On Sat, Jul 06 2024 at 15:27, Marek Vasut wrote:

> This is an RFC patch, I am looking for input on the approach taken here.
> If the approach is sound, this patch would be split into proper patchset.
>
> Various PCIe controllers that mux MSIs onto single IRQ line produce these
> "IRQ%d: set affinity failed" warnings when entering suspend. This has been
> discussed before [1] [2] and an example test case is included at the end
> of this commit message.
>
> Attempt to silence the warning by returning specific error code -EOPNOTSUPP
> from the irqchip .irq_set_affinity callback, which skips printing the warning
> in cpuhotplug.c . The -EOPNOTSUPP was chosen because it indicates exactly what
> the problem is, it is not possible to set affinity of each MSI IRQ line to a
> specific CPU due to hardware limitation.

Why does the irq_chip in question have an irq_set_affinity() callback in
the first place?

Thanks,

        tglx