[PATCH -v12 07/15] PCI: Allocate bus range instead of use max blindly
From: Yinghai Lu
Date: Tue Jun 26 2012 - 14:55:47 EST
Every bus have extra busn_res, and linked them together under root bus busn_res
When need to find usable bus number range, try probe it.
To avoid falling to small hole in the middle, we try from 8 spare bus.
If can not find 8 or more in the middle, will try to append 8 on top later.
then if can not append, will try to find 7 from the middle, then will try to append 7 on top.
then if can not append, will try to find 6 from the middle...
For cardbus will only find 4 spare.
If extend from top, at last will shrink back to really needed range...
-v4: fix checking with pci rescan. Found by Bjorn.
-v5: Use update bridge probe busn_res function and replace_resource
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
---
drivers/pci/probe.c | 100 ++++++++++++++++++++++++++++-----------------------
1 files changed, 55 insertions(+), 45 deletions(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 7498502..1cae8fe 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -638,9 +638,8 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
* Set up the primary, secondary and subordinate
* bus numbers.
*/
- child->number = child->busn_res.start = busnr;
+ child->number = busnr;
child->primary = parent->busn_res.start;
- child->busn_res.end = 0xff;
if (!bridge)
return child;
@@ -774,10 +773,11 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
{
struct pci_bus *child;
int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS);
- u32 buses, i, j = 0;
+ u32 buses;
u16 bctl;
u8 primary, secondary, subordinate;
int broken = 0;
+ struct resource *parent_res = NULL;
pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
primary = buses & 0xFF;
@@ -794,10 +794,11 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
/* Check if setup is sensible at all */
if (!pass &&
- (primary != bus->number || secondary <= bus->number)) {
- dev_dbg(&dev->dev, "bus configuration invalid, reconfiguring\n");
+ (primary != bus->number || secondary <= bus->number))
broken = 1;
- }
+
+ if (broken)
+ dev_dbg(&dev->dev, "bus configuration invalid, reconfiguring\n");
/* Disable MasterAbortMode during probing to avoid reporting
of bus errors (in some architectures) */
@@ -842,6 +843,11 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
* We need to assign a number to this bus which we always
* do in the second pass.
*/
+ long shrink_size;
+ struct resource busn_res;
+ int ret = -ENOMEM;
+ int old_max = max;
+
if (!pass) {
if (pcibios_assign_all_busses() || broken)
/* Temporarily disable forwarding of the
@@ -858,21 +864,42 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
/* Clear errors */
pci_write_config_word(dev, PCI_STATUS, 0xffff);
- /* Prevent assigning a bus number that already exists.
- * This can happen when a bridge is hot-plugged, so in
- * this case we only re-scan this bus. */
- child = pci_find_bus(pci_domain_nr(bus), max+1);
- if (!child) {
- child = pci_add_new_bus(bus, dev, ++max);
- if (!child)
- goto out;
- pci_bus_insert_busn_res(child, max, 0xff);
+ if (dev->subordinate) {
+ /* We get here only for cardbus */
+ child = dev->subordinate;
+ if (!is_cardbus)
+ dev_warn(&dev->dev,
+ "rescan scaned bridge as broken one again ?");
+
+ goto out;
}
+ /*
+ * For CardBus bridges, we leave 4 bus numbers
+ * as cards with a PCI-to-PCI bridge can be
+ * inserted later.
+ * other just allocate 8 bus to avoid we fall into
+ * small hole in the middle.
+ */
+ ret = pci_bridge_probe_busn_res(bus, dev, &busn_res,
+ is_cardbus ? (CARDBUS_RESERVE_BUSNR + 1) : 8,
+ &parent_res);
+
+ if (ret != 0)
+ goto out;
+
+ child = pci_add_new_bus(bus, dev, busn_res.start);
+ if (!child)
+ goto out;
+
+ pci_bus_replace_busn_res(child, &busn_res);
+
buses = (buses & 0xff000000)
| ((unsigned int)(child->primary) << 0)
| ((unsigned int)(child->busn_res.start) << 8)
| ((unsigned int)(child->busn_res.end) << 16);
+ max = child->busn_res.end;
+
/*
* yenta.c forces a secondary latency timer of 176.
* Copy that behaviour here.
@@ -903,43 +930,26 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
* the real value of max.
*/
pci_fixup_parent_subordinate_busnr(child, max);
+
} else {
- /*
- * For CardBus bridges, we leave 4 bus numbers
- * as cards with a PCI-to-PCI bridge can be
- * inserted later.
- */
- for (i=0; i<CARDBUS_RESERVE_BUSNR; i++) {
- struct pci_bus *parent = bus;
- if (pci_find_bus(pci_domain_nr(bus),
- max+i+1))
- break;
- while (parent->parent) {
- if ((!pcibios_assign_all_busses()) &&
- (parent->busn_res.end > max) &&
- (parent->busn_res.end <= max+i)) {
- j = 1;
- }
- parent = parent->parent;
- }
- if (j) {
- /*
- * Often, there are two cardbus bridges
- * -- try to leave one valid bus number
- * for each one.
- */
- i /= 2;
- break;
- }
- }
- max += i;
pci_fixup_parent_subordinate_busnr(child, max);
}
/*
* Set the subordinate bus number to its real value.
*/
- pci_bus_update_busn_res_end(child, max);
+ shrink_size = (int)child->busn_res.end - max;
pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max);
+ pci_bus_update_busn_res_end(child, max);
+
+ /* shrink some back, if we extend top before */
+ if (!is_cardbus && (shrink_size > 0) && parent_res) {
+ resource_shrink_parents_top(&bus->busn_res, shrink_size,
+ parent_res);
+ pci_bus_shrink_top(bus, shrink_size, parent_res);
+ }
+
+ if (old_max > max)
+ max = old_max;
}
sprintf(child->name,
--
1.7.7
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