Re: [PATCH v2 0/5] PCI: dwc: improve msi handling

[Jisheng Zhang]

Hi Jon,

On Fri, 25 Sep 2020 09:53:45 +0100 Jon Hunter wrote:

> 
> On 24/09/2020 12:05, Jisheng Zhang wrote:
> > Improve the msi code:
> > 1. Add proper error handling.
> > 2. Move dw_pcie_msi_init() from each users to designware host to solve
> > msi page leakage in resume path.  
> 
> Apologies if this is slightly off topic, but I have been meaning to ask
> about MSIs and PCI. On Tegra194 which uses the DWC PCI driver, whenever we
> hotplug CPUs we see the following warnings ...
> 
>  [      79.068351] WARNING KERN IRQ70: set affinity failed(-22).
>  [      79.068362] WARNING KERN IRQ71: set affinity failed(-22).
> 

I tried to reproduce this issue on Synaptics SoC, but can't reproduce it.
Per my understanding of the code in kernel/irq/cpuhotplug.c, this warning
happened when we migrate irqs away from the offline cpu, this implicitly
implies that before this point the irq has bind to the offline cpu, but how
could this happen given current dw_pci_msi_set_affinity() implementation
always return -EINVAL

thanks