Kernel 5.16.3 and above fails to detect PCIe devices on Turris Omnia (Armada 385 / mvebu)

[Bjorn Helgaas]

On Thu, Feb 24, 2022 at 05:00:30PM +0100, Marcel Menzel wrote:
> +linux-pci
> 
> Am 24.02.2022 um 14:52 schrieb Marcel Menzel:
> > Am 24.02.2022 um 14:09 schrieb Marcel Menzel:
> > > Hello,
> > > 
> > > When upgrading from kernel 5.16.2 to a newer version (tried 5.16.3
> > > and 5.16.10 with unchanged .config), the Kernel fails to detect both
> > > my installed mPCIe WiFi cards in my Turris Omnia (newer version,
> > > silver case, GPIO pins installed again).
> > > I have two Mediatek MT7915 based cards installed. I also tried with
> > > one Atheros at9k and one ath10k based card, yielding the same
> > > result. On a Kernel version newer than 5.16.2, all cards aren't
> > > getting recognized correctly.
> > > 
> > > Before 5.16.3 I also had to disable PCIe ASPM via boot aragument,
> > > otherwise the WiFi drivers would complain about weird device
> > > behaviors and failing to initialize them, but re-enabling it does
> > > not yield any different results.

Please try this commit, which is headed to mainline today:

https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/commit/?h=for-linus&id=c49ae619905eebd3f54598a84e4cd2bd58ba8fe9

This commit should fix the PCI enumeration problem.  If you still have
to disable ASPM, that sounds like a separate problem that we should
also try to debug.

Bjorn