Re: [PATCH] usb: xhci: Restore MSI/MSI-X reinitialization on resume for RESET_ON_RESUME hosts

[Michal Pecio <michal.pecio@gmail.com>]

To avoid putting PCI-specific code in xhci.c, I wonder if it would
still work if the disable/enable cycle is done by xhci_pci_resume()
before calling xhci_resume()?

On Thu, 30 Jul 2026 10:24:05 +0800, Jie Deng wrote:
> Runtime PM is not practically triggerable on this desktop setup,
> but code inspection shows runtime resume also goes through
> xhci_resume() with reset_registers=true for XHCI_RESET_ON_RESUME
> hosts.

Resetting at runtime resume sounds like an odd thing to do, maybe
runtime suspend should be rejected then. But this is unrelated...

> We conducted 1000 tests on Hibernate and did not observe the problem 
> recurring.
> When it is suspended, both xHC D3hot and D3clod can reproduce the
> problem.

> Additionally, I was able to reproduce the problem using the Renesas 
> uPD720201 controller as well.

I wonder if it's an issue with those chips or a general PCIe or IRQ
resume bug in some particular host system? It looks like nobody else
complained about this old patch for three years.

I don't have ASM3042, but I do have ASM1042, ASM1142, ASM3142 and
also uPD720200, uPD720201 (rarely available for testing), uPD720202.
To be honest, I have never seen lost IRQs after resume here.

How often is this supposed to happen, how exactly is it reproduced?

Regards,
Michal