PCI: Delay enabling bridges until they're needed
We currently enable PCI bridges after scanning a bus and assigning
resources. This is often done in arch code.
This patch changes this so we don't enable a bridge until necessary, i.e.,
until we enable a PCI device behind the bridge. We do this in the generic
pci_enable_device() path, so this also removes the arch-specific code to
enable bridges.
[bhelgaas: changelog]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index b1ff02a..fc1b740 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -216,24 +216,6 @@
}
}
-void pci_enable_bridges(struct pci_bus *bus)
-{
- struct pci_dev *dev;
- int retval;
-
- list_for_each_entry(dev, &bus->devices, bus_list) {
- if (dev->subordinate) {
- if (!pci_is_enabled(dev)) {
- retval = pci_enable_device(dev);
- if (retval)
- dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n", retval);
- pci_set_master(dev);
- }
- pci_enable_bridges(dev->subordinate);
- }
- }
-}
-
/** pci_walk_bus - walk devices on/under bus, calling callback.
* @top bus whose devices should be walked
* @cb callback to be called for each device found
@@ -301,4 +283,3 @@
EXPORT_SYMBOL(pci_bus_alloc_resource);
EXPORT_SYMBOL_GPL(pci_bus_add_device);
EXPORT_SYMBOL(pci_bus_add_devices);
-EXPORT_SYMBOL(pci_enable_bridges);
diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 59df857..52dee9d 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -723,7 +723,6 @@
acpiphp_sanitize_bus(bus);
acpiphp_set_hpp_values(bus);
acpiphp_set_acpi_region(slot);
- pci_enable_bridges(bus);
list_for_each_entry(dev, &bus->devices, bus_list) {
/* Assume that newly added devices are powered on already. */
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e37fea6..44a1a8a 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1145,6 +1145,24 @@
return 0;
}
+static void pci_enable_bridge(struct pci_dev *dev)
+{
+ int retval;
+
+ if (!dev)
+ return;
+
+ pci_enable_bridge(dev->bus->self);
+
+ if (pci_is_enabled(dev))
+ return;
+ retval = pci_enable_device(dev);
+ if (retval)
+ dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n",
+ retval);
+ pci_set_master(dev);
+}
+
static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
{
int err;
@@ -1165,6 +1183,8 @@
if (atomic_inc_return(&dev->enable_cnt) > 1)
return 0; /* already enabled */
+ pci_enable_bridge(dev->bus->self);
+
/* only skip sriov related */
for (i = 0; i <= PCI_ROM_RESOURCE; i++)
if (dev->resource[i].flags & flags)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 46ada5c..85c114c 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1979,7 +1979,6 @@
max = pci_scan_child_bus(bus);
pci_assign_unassigned_bus_resources(bus);
- pci_enable_bridges(bus);
pci_bus_add_devices(bus);
return max;
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 4d9ebb4..8f86be1 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1440,7 +1440,7 @@
/* any device complain? */
if (list_empty(&fail_head))
- goto enable_and_dump;
+ goto dump;
if (tried_times >= pci_try_num) {
if (enable_local == undefined)
@@ -1449,7 +1449,7 @@
dev_info(&bus->dev, "Automatically enabled pci realloc, if you have problem, try booting with pci=realloc=off\n");
free_list(&fail_head);
- goto enable_and_dump;
+ goto dump;
}
dev_printk(KERN_DEBUG, &bus->dev,
@@ -1482,10 +1482,7 @@
goto again;
-enable_and_dump:
- /* Depth last, update the hardware. */
- pci_enable_bridges(bus);
-
+dump:
/* dump the resource on buses */
pci_bus_dump_resources(bus);
}
@@ -1556,7 +1553,6 @@
if (retval)
dev_err(&bridge->dev, "Error reenabling bridge (%d)\n", retval);
pci_set_master(bridge);
- pci_enable_bridges(parent);
}
EXPORT_SYMBOL_GPL(pci_assign_unassigned_bridge_resources);