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powerpc/pci: Unroll two pass loop when scanning bridges

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The current scanning code is really hard to understand because it calls the
same function in a loop where pass value is changed without any comments
explaining it:

  for (pass = 0; pass < 2; pass++)
    for_each_pci_bridge(dev, bus)
      max = pci_scan_bridge(bus, dev, max, pass);

Unfamiliar reader cannot tell easily what is the purpose of this loop
without looking at internals of pci_scan_bridge().

In order to make this bit easier to understand, open-code the loop in
pci_scan_child_bus() and pci_hp_add_bridge() with added comments.

No functional changes intended.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
This commit is contained in:
Andy Shevchenko
2017-11-10 19:52:30 +02:00
committed by Bjorn Helgaas
parent dd1ea5763e
commit 9d987eba8e
1 changed files with 12 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
arch/powerpc/kernel/pci-hotplug.c
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@@ -104,7 +104,7 @@ EXPORT_SYMBOL_GPL(pci_hp_remove_devices);
*/ */
void pci_hp_add_devices(struct pci_bus *bus) void pci_hp_add_devices(struct pci_bus *bus)
{ {
int slotno, mode, pass, max; int slotno, mode, max;
struct pci_dev *dev; struct pci_dev *dev;
struct pci_controller *phb; struct pci_controller *phb;
struct device_node *dn = pci_bus_to_OF_node(bus); struct device_node *dn = pci_bus_to_OF_node(bus);
@@ -133,10 +133,17 @@ void pci_hp_add_devices(struct pci_bus *bus)
pci_scan_slot(bus, PCI_DEVFN(slotno, 0)); pci_scan_slot(bus, PCI_DEVFN(slotno, 0));
pcibios_setup_bus_devices(bus); pcibios_setup_bus_devices(bus);
max = bus->busn_res.start; max = bus->busn_res.start;
for (pass = 0; pass < 2; pass++) { /*
for_each_pci_bridge(dev, bus) * Scan bridges that are already configured. We don't touch
max = pci_scan_bridge(bus, dev, max, pass); * them unless they are misconfigured (which will be done in
} * the second scan below).
*/
for_each_pci_bridge(dev, bus)
max = pci_scan_bridge(bus, dev, max, 0);
/* Scan bridges that need to be reconfigured */
for_each_pci_bridge(dev, bus)
max = pci_scan_bridge(bus, dev, max, 1);
} }
pcibios_finish_adding_to_bus(bus); pcibios_finish_adding_to_bus(bus);
} }