On Fri, Nov 25, 2016 at 11:57:09AM +0100, Thierry Reding wrote: > From: Arnd Bergmann <arnd@xxxxxxxx> > > This patch makes the existing pci_host_bridge structure a proper device > that is usable by PCI host drivers in a more standard way. In addition > to the existing pci_scan_bus, pci_scan_root_bus, pci_scan_root_bus_msi, > and pci_create_root_bus interfaces, this unfortunately means having to > add yet another interface doing basically the same thing, and add some > extra code in the initial step. > > However, this time it's more likely to be extensible enough that we > won't have to do another one again in the future, and we should be > able to reduce code much more as a result. > > The main idea is to pull the allocation of 'struct pci_host_bridge' out > of the registration, and let individual host drivers and architecture > code fill the members before calling the registration function. I really like this idea. Can you include pointers to similar interfaces in other subsystems? I'm hoping to reuse existing designs as much as possible, including using similar names. > There are a number of things we can do based on this: > > * Use a single memory allocation for the driver-specific structure > and the generic PCI host bridge > * consolidate the contents of driver specific structures by moving > them into pci_host_bridge > * Add a consistent interface for removing a PCI host bridge again > when unloading a host driver module > * Replace the architecture specific __weak pcibios_* functions with > callbacks in a pci_host_bridge device > * Move common boilerplate code from host drivers into the generic > function, based on contents of the structure > * Extend pci_host_bridge with additional members when needed without > having to add arguments to pci_scan_*. > * Move members of struct pci_bus into pci_host_bridge to avoid > having lots of identical copies. > > As mentioned in a previous email, one open question is whether we want > to export a function for allocating a pci_host_bridge device in > combination with the per-device structure or let the driver itself > call kzalloc. The next patch implements the former, doesn't it? If this is no longer an open question, let's update this changelog. > Changes in v3 (Thierry Reding): > - swap out pci_host_bridge_init() for pci_alloc_host_bridge() with an > extra parameter specifying the size of the driver's private data > - rename pci_host_bridge_register() to pci_register_host_bridge() for > more consistency with existing functions > - split patches into smaller chunks to make diff more readable > > Changes in v2 (Thierry Reding): > - add a pci_host_bridge_init() helper that drivers can use to perform > all the necessary steps to initialize the bridge > - rename pci_register_host() to pci_host_bridge_register() to reflect > the naming used by other functions > - plug memory leak on registration failure You can also omit these v2/v3 change comments from the changelog; it's useful to have them in a 0/n cover letter or after the "---" line in an individual patch. I omit them from the git changelogs because they're not very useful after the patches get merged. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
