Messages in this thread | | | Date | Thu, 20 Nov 2014 12:54:48 +0100 | From | Tomasz Nowicki <> | Subject | Re: [RFC PATCH 00/16] Refine PCI host bridge scan interfaces |
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On 17.11.2014 15:13, Arnd Bergmann wrote: > On Monday 17 November 2014 18:21:34 Yijing Wang wrote: >> This series is based Linux 3.18-rc1 and Lorenzo Pieralisi's >> arm PCI domain cleanup patches, link: >> https://patchwork.ozlabs.org/patch/407585/ >> >> Current pci scan interfaces like pci_scan_root_bus() and directly >> call pci_create_root_bus()/pci_scan_child_bus() lack flexiblity. >> Some platform infos like PCI domain and msi_chip have to be >> associated to PCI bus by some arch specific function. >> We want to make a generic pci_host_bridge, and make it hold >> the platform infos or hook. Then we could eliminate the lots >> of arch pci_domain_nr, also we could associate some platform >> ops something like pci_get_msi_chip(struct pci_dev *dev) >> with pci_host_bridge to avoid introduce arch weak functions. >> >> This RFC version not for all platforms, just applied the new >> scan interface in x86/arm/powerpc/ia64, I will refresh other >> platforms after the core pci scan interfaces are ok. > > I think overall this is a good direction to take, in particular > moving more things into struct pci_host_bridge so we can > slim down the architecture specific code. > > I don't particularly like the way you use the 'pci_host_info' > to pass callback pointers and some of the generic information. > This duplicates some of the issues we are currently trying > to untangle in the arm32 code to make drivers easier to share > between architectures. > > As a general approach, I'd rather see generic helper functions > being exported by the PCI core that a driver may or may not > call. > The way you split the interface between things that happen > before scanning the buses (pci_create_host_bridge) and > the actual scanning (__pci_create_root_bus, pci_scan_child_bus) > seems very helpful and I think we can expand that concept further: > > - The normal pci_create_host_bridge() function can contain > all of the DT scanning functions (finding bus/mem/io resources, > finding the msi-parent), while drivers that don't depend on DT > for this information can call the same function and fill the > same things after they have the pci_host_bridge pointer.
How about finding PCI domain number (in the DT way) within pci_create_host_bridge() too ?
Tomasz
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