static void quirk_system_pci_resources()

in quirks.c [229:298]

• 37 lines of code
• 11 McCabe index (conditional complexity)

static void quirk_system_pci_resources(struct pnp_dev *dev)
{
	struct pci_dev *pdev = NULL;
	struct resource *res;
	resource_size_t pnp_start, pnp_end, pci_start, pci_end;
	int i, j;

	/*
	 * Some BIOSes have PNP motherboard devices with resources that
	 * partially overlap PCI BARs.  The PNP system driver claims these
	 * motherboard resources, which prevents the normal PCI driver from
	 * requesting them later.
	 *
	 * This patch disables the PNP resources that conflict with PCI BARs
	 * so they won't be claimed by the PNP system driver.
	 */
	for_each_pci_dev(pdev) {
		for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
			unsigned long flags, type;

			flags = pci_resource_flags(pdev, i);
			type = flags & (IORESOURCE_IO | IORESOURCE_MEM);
			if (!type || pci_resource_len(pdev, i) == 0)
				continue;

			if (flags & IORESOURCE_UNSET)
				continue;

			pci_start = pci_resource_start(pdev, i);
			pci_end = pci_resource_end(pdev, i);
			for (j = 0;
			     (res = pnp_get_resource(dev, type, j)); j++) {
				if (res->start == 0 && res->end == 0)
					continue;

				pnp_start = res->start;
				pnp_end = res->end;

				/*
				 * If the PNP region doesn't overlap the PCI
				 * region at all, there's no problem.
				 */
				if (pnp_end < pci_start || pnp_start > pci_end)
					continue;

				/*
				 * If the PNP region completely encloses (or is
				 * at least as large as) the PCI region, that's
				 * also OK.  For example, this happens when the
				 * PNP device describes a bridge with PCI
				 * behind it.
				 */
				if (pnp_start <= pci_start &&
				    pnp_end >= pci_end)
					continue;

				/*
				 * Otherwise, the PNP region overlaps *part* of
				 * the PCI region, and that might prevent a PCI
				 * driver from requesting its resources.
				 */
				dev_warn(&dev->dev,
					 "disabling %pR because it overlaps "
					 "%s BAR %d %pR\n", res,
					 pci_name(pdev), i, &pdev->resource[i]);
				res->flags |= IORESOURCE_DISABLED;
			}
		}
	}
}