Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | Re: [PATCH v3 3/6] PCI: generic: Quit clobbering our pci_ops. | Date | Wed, 23 Sep 2015 10:21:10 +0200 |
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On Tuesday 22 September 2015 16:49:14 David Daney wrote: > From: David Daney <david.daney@cavium.com> > > The pci-host-generic driver keeps a global struct pci_ops which it > then patches with the .map_bus method appropriate for the bus device. > A problem arises when the driver is used for two different types of > bus devices, the .map_bus method for the last device probed clobbers > the method for all previous devices. The result, only the last bus > device probed has the proper .map_bus, and the others fail. > > Move the struct pci_ops into the bus specific structure, and > initialize it when the bus device is probed. Keep a copy of the > gen_pci_cfg_bus_ops structure, instead of a pointer to a global copy,
This is a very useful change.
> to future proof against the addition of bus specific elements to > struct pci_ops.
but I don't like this part. We should just not have bus specific elements in pci_ops. We don't really have that here either, except that the gen_pci driver had a hack for reusing the same operations for things that are actually different.
It's an established practice that anything named '*_operations' is meant to be constant and ideally defined as 'static const ... *_ops;' in the driver. We could try to enforce this better by marking bus->ops as 'const' and changing all the instances of this structure accordingly.
> @@ -65,7 +65,11 @@ static void __iomem *gen_pci_map_cfg_bus_cam(struct pci_bus *bus, > > static struct gen_pci_cfg_bus_ops gen_pci_cfg_cam_bus_ops = { > .bus_shift = 16, > - .map_bus = gen_pci_map_cfg_bus_cam, > + .ops = { > + .map_bus = gen_pci_map_cfg_bus_cam, > + .read = pci_generic_config_read, > + .write = pci_generic_config_write, > + } > };
So this is good. We could in theory unify the map_bus functions like this now:
static void __iomem *gen_pci_map_cfg_bus(struct pci_bus *bus, unsigned int devfn, int where) { struct gen_pci *pci = bus->sysdata; struct gen_pci_cfg_bus_ops *ops; resource_size_t idx;
ops = container_of(bus->ops, struct gen_pci_cfg_bus_ops, ops); idx = bus->number - pci->cfg.bus_range->start;
return pci->cfg.win[idx] + ((devfn << ops->dev_shift) | where); }
Not sure if that improves clarity or not, up to Will.
> @@ -234,8 +237,7 @@ static int gen_pci_probe(struct platform_device *pdev) > } > > of_id = of_match_node(gen_pci_of_match, np); > - pci->cfg.ops = of_id->data; > + pci->cfg.ops = *(struct gen_pci_cfg_bus_ops *)of_id->data;
This is the part that grabbed my attention, we should not do it like this.
Arnd
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