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PCI: Open-code the two pass loop when scanning bridges 

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: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Mika Westerberg 2017-10-13 21:35:42 +03:00 committed by Bjorn Helgaas
parent 95e3ba9772
commit 4147c2fd9b
1 changed files with 20 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/pci/probe.c
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@ -2398,7 +2398,7 @@ void __weak pcibios_fixup_bus(struct pci_bus *bus)
unsigned int pci_scan_child_bus(struct pci_bus *bus)
{
unsigned int devfn, pass, max = bus->busn_res.start;
unsigned int devfn, max = bus->busn_res.start;
struct pci_dev *dev;
dev_dbg(&bus->dev, "scanning bus\n");
@ -2420,9 +2420,17 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus)
bus->is_added = 1;
}
for (pass = 0; pass < 2; pass++)
for_each_pci_bridge(dev, bus)
max = pci_scan_bridge(bus, dev, max, pass);
/*
* Scan bridges that are already configured. We don't touch 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);
/*
* Make sure a hotplug bridge has at least the minimum requested
@ -2739,7 +2747,7 @@ void __init pci_sort_breadthfirst(void)
int pci_hp_add_bridge(struct pci_dev *dev)
{
struct pci_bus *parent = dev->bus;
int pass, busnr, start = parent->busn_res.start;
int busnr, start = parent->busn_res.start;
int end = parent->busn_res.end;
for (busnr = start; busnr <= end; busnr++) {
@ -2750,8 +2758,13 @@ int pci_hp_add_bridge(struct pci_dev *dev)
dev_err(&dev->dev, "No bus number available for hot-added bridge\n");
return -1;
}
for (pass = 0; pass < 2; pass++)
busnr = pci_scan_bridge(parent, dev, busnr, pass);
/* Scan bridges that are already configured */
busnr = pci_scan_bridge(parent, dev, busnr, 0);
/* Scan bridges that need to be reconfigured */
pci_scan_bridge(parent, dev, busnr, 1);
if (!dev->subordinate)
return -1;