Re: [Bug 215540] New: mvebu: no pcie devices detected on turris omnia (5.16.3 regression)

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Feb 11, 2022 at 08:43:30PM +0100, Pali Rohár wrote:
> On Thursday 03 February 2022 09:47:28 Bjorn Helgaas wrote:
> > [+cc Lorenzo, beginning of thread:
> > https://lore.kernel.org/r/20220127234917.GA150851@bhelgaas]
> > On Thu, Feb 03, 2022 at 01:55:28PM +0100, Pali Rohár wrote:

> > > Bjorn & Greg: How do you want to handle this situation? Should I prepare
> > > special patch for stable which fix it? Or something else?
> > > 
> > > Anyway, do you know how it could happen that patch was incorrectly
> > > auto-backported into stable? Differences between original and
> > > wrongly-modified patch looks very similar (both "bus" and "dev" keywords
> > > have same number of characters) and it was hard for me to see that there
> > > are differences. So probably overlooking could happen or maybe git or
> > > patch tools could do such small changes when doing backports?
> > 
> > Your patch on the mailing list [1] contains:
> > 
> >         mvebu_pcie_setup_hw(port);
> >         mvebu_pcie_set_local_dev_nr(port, 1);
> >   +     mvebu_pcie_set_local_bus_nr(port, 0);
> > 
> > 91a8d79fc797 ("PCI: mvebu: Fix configuring secondary bus of PCIe Root
> > Port via emulated bridge") [2] appeared in v5.17-rc1 and contains:
> > 
> >         mvebu_pcie_setup_hw(port);
> >   -     mvebu_pcie_set_local_dev_nr(port, 1);
> >   +     mvebu_pcie_set_local_dev_nr(port, 0);
> > 
> > And this is the current state of mainline [3].
> > 
> > 91a8d79fc797 was backported to v5.16.3 as 7cde9bf07316 [4], which also
> > contains:
> > 
> >         mvebu_pcie_setup_hw(port);
> >   -     mvebu_pcie_set_local_dev_nr(port, 1);
> >   +     mvebu_pcie_set_local_dev_nr(port, 0);
> > 
> > So I think the problem was a merge error when we first applied this
> > for mainline, and we just need to make a patch for mainline, apply it
> > for v5.17, and mark it for stable.
> 
> Should I prepare and send fixup patch?

Yes, please.  Sorry for the inconvenience!

> > [1] https://lore.kernel.org/r/20211125124605.25915-12-pali@kernel.org
> > [2] https://git.kernel.org/linus/91a8d79fc797
> > [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pci-mvebu.c?id=v5.17-rc2#n1323
> > [4] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.16.y&id=7cde9bf07316