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).
Root Cause Analysis: 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 gets
invoked from pci_hp_add_devices(). This new function
pci_traverse_sibling_nodes_and_scan_slot() gets all the sibling
bridge-ports by traversal and explicitly invokes pci_scan_slot on them.
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Gaurav Batra <gbatra@xxxxxxxxxxxxx>
Cc: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
Cc: Brian King <brking@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Krishna Kumar <krishnak@xxxxxxxxxxxxx>
---
arch/powerpc/include/asm/ppc-pci.h | 4 ++++
arch/powerpc/kernel/pci-hotplug.c | 5 ++---
arch/powerpc/kernel/pci_dn.c | 32 ++++++++++++++++++++++++++++++
3 files changed, 38 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/include/asm/ppc-pci.h b/arch/powerpc/include/asm/ppc-pci.h
index a8b7e8682f5b..83db8d0798ac 100644
--- a/arch/powerpc/include/asm/ppc-pci.h
+++ b/arch/powerpc/include/asm/ppc-pci.h
@@ -28,6 +28,10 @@ struct pci_dn;
void *pci_traverse_device_nodes(struct device_node *start,
void *(*fn)(struct device_node *, void *),
void *data);
+
+void pci_traverse_sibling_nodes_and_scan_slot(struct device_node *start,
+ struct pci_bus *bus);
+
extern void pci_devs_phb_init_dynamic(struct pci_controller *phb);
#if defined(CONFIG_IOMMU_API) && (defined(CONFIG_PPC_PSERIES) || \
diff --git a/arch/powerpc/kernel/pci-hotplug.c b/arch/powerpc/kernel/pci-hotplug.c
index 0fe251c6ac2c..639a3d592fe2 100644
--- a/arch/powerpc/kernel/pci-hotplug.c
+++ b/arch/powerpc/kernel/pci-hotplug.c
@@ -106,7 +106,7 @@ 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 +129,7 @@ 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));
+ pci_traverse_sibling_nodes_and_scan_slot(dn, bus);
max = bus->busn_res.start;
/*
* Scan bridges that are already configured. We don't touch
diff --git a/arch/powerpc/kernel/pci_dn.c b/arch/powerpc/kernel/pci_dn.c
index 38561d6a2079..bea612759832 100644
--- a/arch/powerpc/kernel/pci_dn.c
+++ b/arch/powerpc/kernel/pci_dn.c
@@ -493,4 +493,36 @@ static void pci_dev_pdn_setup(struct pci_dev *pdev)
pdn = pci_get_pdn(pdev);
pdev->dev.archdata.pci_data = pdn;
}
+
+void pci_traverse_sibling_nodes_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));
+ }
+ }
+ }
+
+}
+
DECLARE_PCI_FIXUP_EARLY(PCI_ANY_ID, PCI_ANY_ID, pci_dev_pdn_setup);
--
2.45.0
