On Tuesday 22 September 2015 16:49:14 David Daney wrote:
> From: David Daney <david.daney@xxxxxxxxxx>
>
> 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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