Commit 20ce0c24 authored by Krishna Kumar's avatar Krishna Kumar Committed by Michael Ellerman
Browse files

powerpc/pci: Hotplug driver bridge support 



There is an issue with the hotplug operation when it's done on the
bridge/switch slot. The bridge-port and devices behind the bridge, which
become offline by hot-unplug operation, don't get hot-plugged/enabled
by doing hot-plug operation on that slot. Only the first port of the
bridge gets enabled and the remaining port/devices remain unplugged. The
hot plug/unplug operation is done by the hotplug driver (drivers/pci/
hotplug/pnv_php.c).

This behavior is due to missing code for the switch/bridge. The existing
driver depends on pci_hp_add_devices() function for device enablement.
This function calls pci_scan_slot() on only one device-node/port of the
bridge, not on all the siblings' device-node/port.

The missing code needs to be added which will find all the sibling
device-nodes/bridge-ports and will run explicit pci_scan_slot()
on those. A new function has been added for this purpose
which is invoked from pci_hp_add_devices(). This new function
traverse_siblings_and_scan_slot() gets all the sibling bridge-ports by
traversal and explicitly invokes pci_scan_slot() on them.

Tested-by: default avatarShawn Anastasio <sanastasio@raptorengineering.com>
Signed-off-by: default avatarKrishna Kumar <krishnak@linux.ibm.com>
[mpe: Move the code into pci-hotplug.c]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240701074513.94873-3-krishnak@linux.ibm.com
parent 335e35b7

arch/powerpc/kernel/pci-hotplug.c

+32 −3
Original line number Diff line number Diff line
@@ -93,6 +93,36 @@ void pci_hp_remove_devices(struct pci_bus *bus) 
}

EXPORT_SYMBOL_GPL(pci_hp_remove_devices);



static void traverse_siblings_and_scan_slot(struct device_node *start, struct pci_bus *bus)

{

	struct device_node *dn;

	int slotno;



	u32 class = 0;



	if (!of_property_read_u32(start->child, "class-code", &class)) {

		/* Call of pci_scan_slot for non-bridge/EP case */

		if (!((class >> 8) == PCI_CLASS_BRIDGE_PCI)) {

			slotno = PCI_SLOT(PCI_DN(start->child)->devfn);

			pci_scan_slot(bus, PCI_DEVFN(slotno, 0));

			return;

		}

	}



	/* Iterate all siblings */

	for_each_child_of_node(start, dn) {

		class = 0;



		if (!of_property_read_u32(start->child, "class-code", &class)) {

			/* Call of pci_scan_slot on each sibling-nodes/bridge-ports */

			if ((class >> 8) == PCI_CLASS_BRIDGE_PCI) {

				slotno = PCI_SLOT(PCI_DN(dn)->devfn);

				pci_scan_slot(bus, PCI_DEVFN(slotno, 0));

			}

		}

	}

}



/**

 * pci_hp_add_devices - adds new pci devices to bus

 * @bus: the indicated PCI bus
@@ -106,7 +136,7 @@ EXPORT_SYMBOL_GPL(pci_hp_remove_devices); 
 */

void pci_hp_add_devices(struct pci_bus *bus)

{

	int slotno, mode, max;

	int mode, max;

	struct pci_dev *dev;

	struct pci_controller *phb;

	struct device_node *dn = pci_bus_to_OF_node(bus);
@@ -129,8 +159,7 @@ void pci_hp_add_devices(struct pci_bus *bus) 
		 * order for fully rescan all the way down to pick them up.

		 * They can have been removed during partial hotplug.

		 */

		slotno = PCI_SLOT(PCI_DN(dn->child)->devfn);

		pci_scan_slot(bus, PCI_DEVFN(slotno, 0));

		traverse_siblings_and_scan_slot(dn, bus);

		max = bus->busn_res.start;

		/*

		 * Scan bridges that are already configured. We don't touch