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/openbmc/linux/arch/powerpc/kernel/ |
H A D | pci_32.c | 56635681 Wed Jul 06 05:43:08 CDT 2022 Pali Rohár <pali@kernel.org> powerpc/pci: Add config option for using all 256 PCI buses
By default on PPC32 PCI bus numbers are unique across all PCI domains. So a system could have only 256 PCI buses independently of available PCI domains.
This is due to filling DT property pci-OF-bus-map which does not support a multi-domain setup.
On all powerpc platforms except chrp and powermac there is no DT property pci-OF-bus-map anymore and therefore it is possible on non-chrp/powermac platforms to avoid this limitation of maximum number of 256 PCI buses in a system even on multi-domain setup.
But avoiding this limitation would mean that all PCI and PCIe devices would be present on completely different BDF addresses as every PCI domain starts numbering PCI bueses from zero (instead of the last bus number of previous enumerated PCI domain). Such change could break existing software which expects fixed PCI bus numbers.
So add a new config option CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT which enables this change. By default it is disabled. It causes the initial value of hose->first_busno to be zero.
Signed-off-by: Pali Rohár <pali@kernel.org> [mpe: Minor change log wording] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220706104308.5390-6-pali@kernel.org
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/openbmc/linux/arch/powerpc/ |
H A D | Kconfig | 56635681 Wed Jul 06 05:43:08 CDT 2022 Pali Rohár <pali@kernel.org> powerpc/pci: Add config option for using all 256 PCI buses
By default on PPC32 PCI bus numbers are unique across all PCI domains. So a system could have only 256 PCI buses independently of available PCI domains.
This is due to filling DT property pci-OF-bus-map which does not support a multi-domain setup.
On all powerpc platforms except chrp and powermac there is no DT property pci-OF-bus-map anymore and therefore it is possible on non-chrp/powermac platforms to avoid this limitation of maximum number of 256 PCI buses in a system even on multi-domain setup.
But avoiding this limitation would mean that all PCI and PCIe devices would be present on completely different BDF addresses as every PCI domain starts numbering PCI bueses from zero (instead of the last bus number of previous enumerated PCI domain). Such change could break existing software which expects fixed PCI bus numbers.
So add a new config option CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT which enables this change. By default it is disabled. It causes the initial value of hose->first_busno to be zero.
Signed-off-by: Pali Rohár <pali@kernel.org> [mpe: Minor change log wording] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220706104308.5390-6-pali@kernel.org
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