On Thursday 25 August 2022 17:49:28 Michael Ellerman wrote:
> Pali Rohár <pali@xxxxxxxxxx> writes:
> > On 32-bit powerpc systems with more PCIe controllers and more PCI domains,
> > where on more PCI domains are same PCI numbers, when kernel is compiled
> > with CONFIG_PROC_FS=y and CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT=y
> > options, kernel prints "proc_dir_entry 'pci/01' already registered" error
> > message.
>
> Thanks, I'll pick this up.
>
> > This regression started appearing after commit 566356813082 ("powerpc/pci:
> > Add config option for using all 256 PCI buses") in case in each mPCIe slot
> > is connected PCIe card and therefore PCI bus 1 is populated in for every
> > PCIe controller / PCI domain.
> >
> > The reason is that PCI procfs code expects that when PCI bus numbers are
> > not unique across all PCI domains, function pci_proc_domain() returns true
> > for domain dependent buses.
> >
> > Fix this issue by setting PCI_ENABLE_PROC_DOMAINS and PCI_COMPAT_DOMAIN_0
> > flags for 32-bit powerpc code when CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
> > is enabled. Same approach is already implemented for 64-bit powerpc code
> > (where PCI bus numbers are always domain dependent).
>
> We also have the same in ppc4xx_pci_find_bridges().
>
> And if we can eventually make CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
> the standard behaviour on 32-bit then everything would behave the same
> and we could simplify pci_proc_domain() to match what other arches do.
I sent two patches which do another steps to achieve it:
https://lore.kernel.org/linuxppc-dev/20220817163927.24453-1-pali@xxxxxxxxxx/t/#u
Main blocker is pci-OF-bus-map which is in direct conflict with
CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT and which used on chrp and pmac.
And I have no idea if pci-OF-bus-map is still needed or not.
> cheers
>
>
> > Fixes: 566356813082 ("powerpc/pci: Add config option for using all 256 PCI buses")
> > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
> > ---
> > arch/powerpc/kernel/pci_32.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/arch/powerpc/kernel/pci_32.c b/arch/powerpc/kernel/pci_32.c
> > index ffc4e1928c80..8acbc9592ebb 100644
> > --- a/arch/powerpc/kernel/pci_32.c
> > +++ b/arch/powerpc/kernel/pci_32.c
> > @@ -249,6 +249,15 @@ static int __init pcibios_init(void)
> >
> > printk(KERN_INFO "PCI: Probing PCI hardware\n");
> >
> > +#ifdef CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
> > + /*
> > + * Enable PCI domains in /proc when PCI bus numbers are not unique
> > + * across all PCI domains to prevent conflicts. And keep PCI domain 0
> > + * backward compatible in /proc for video cards.
> > + */
> > + pci_add_flags(PCI_ENABLE_PROC_DOMAINS | PCI_COMPAT_DOMAIN_0);
> > +#endif
> > +
> > if (pci_has_flag(PCI_REASSIGN_ALL_BUS))
> > pci_assign_all_buses = 1;
> >
> > --
> > 2.20.1
