Commit b91182a6 authored Jul 13, 2013 by Kirill A. Shutemov Committed by Rafael J. Wysocki Jul 23, 2013

ACPI / hotplug / PCI: Allow slots without new devices to be rescanned



Currently, enable_device() checks the return value of pci_scan_slot()
and returns immediately if that's 0 (meaning that no new functions
have been found in the slot).  However, if one of the functions in
the slot is a bridge, some new devices may appear below it even if
the bridge itself is present continuously, so it generally is
necessary to do the rescan anyway just in case.  [In particular,
that's necessary with the Thunderbolt daisy chaining in which case
new devices may be connected to the existing ones down the chain.]

The correctness of this change relies on the ability of
pcibios_resource_survey_bus() to detect if it has already been called
for the given bus and to skip it if so.  Failure to do that will lead
to resource allocation conflicts.

[rjw: Changelog]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent 55502ddb

drivers/pci/hotplug/acpiphp_glue.c

+2 −9

Original line number	Original line	Diff line number	Diff line
	@@ -542,18 +542,13 @@ static int __ref enable_device(struct acpiphp_slot *slot)
	struct pci_dev *dev;		struct pci_dev *dev;
	struct pci_bus *bus = slot->bus;		struct pci_bus *bus = slot->bus;
	struct acpiphp_func *func;		struct acpiphp_func *func;
	int num, max, pass;		int max, pass;
	LIST_HEAD(add_list);		LIST_HEAD(add_list);

	list_for_each_entry(func, &slot->funcs, sibling)		list_for_each_entry(func, &slot->funcs, sibling)
	acpiphp_bus_add(func_to_handle(func));		acpiphp_bus_add(func_to_handle(func));

	num = pci_scan_slot(bus, PCI_DEVFN(slot->device, 0));		pci_scan_slot(bus, PCI_DEVFN(slot->device, 0));
	if (num == 0) {
	/* Maybe only part of funcs are added. */
	dbg("No new device found\n");
	goto err_exit;
	}

	max = acpiphp_max_busnr(bus);		max = acpiphp_max_busnr(bus);
	for (pass = 0; pass < 2; pass++) {		for (pass = 0; pass < 2; pass++) {
	@@ -599,8 +594,6 @@ static int __ref enable_device(struct acpiphp_slot *slot)
	}		}
	}		}


	err_exit:
	return 0;		return 0;
	}		}