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powerpc/pci: Hotplug driver bridge support

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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: Shawn Anastasio <sanastasio@raptorengineering.com>
Signed-off-by: Krishna Kumar <krishnak@linux.ibm.com>
[mpe: Move the code into pci-hotplug.c]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240701074513.94873-3-krishnak@linux.ibm.com
This commit is contained in:
Krishna Kumar 2024-07-01 13:15:07 +05:30 committed by Michael Ellerman
parent 335e35b748
commit 20ce0c247b
1 changed files with 32 additions and 3 deletions
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35
arch/powerpc/kernel/pci-hotplug.c
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@ -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