[PATCH 13/23] PCI: Allocate bus range instead of use max blindly

Yinghai Lu
2012-02-24T10:20:08Z

every bus have extra busn_res, and linked them toghter to iobusn_resource.

when need to find usable bus number range, try probe from iobusn_resource tree.

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.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
drivers/pci/probe.c | 100 ++++++++++++++++++++++++++++++---------------------
1 files changed, 59 insertions(+), 41 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 19aa415..0718ed3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -808,10 +808,11 @@ 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;
@@ -828,10 +829,16 @@ 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;
- }
+
+ /* more strict checking */
+ if (!pass && !broken && !dev->subordinate)
+ broken = pci_bridge_check_busn_broken(bus, dev,
+ secondary, subordinate);
+
+ if (broken)
+ dev_dbg(&dev->dev, "bus configuration invalid, reconfiguring\n");

/* Disable MasterAbortMode during probing to avoid reporting
of bus errors (in some architectures) */
@@ -864,6 +871,8 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
child->primary = primary;
child->subordinate = subordinate;
child->bridge_ctl = bctl;
+
+ pci_bus_insert_busn_res(child, secondary, subordinate);
}

cmax = pci_scan_child_bus(child);
@@ -876,6 +885,11 @@ 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
@@ -892,20 +906,43 @@ 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;
+ 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;
+
+ child->subordinate = busn_res.end;
+ pci_bus_insert_busn_res(child, busn_res.start, busn_res.end);
+
buses = (buses & 0xff000000)
| ((unsigned int)(child->primary) << 0)
| ((unsigned int)(child->secondary) << 8)
| ((unsigned int)(child->subordinate) << 16);

+ max = child->subordinate;
+
/*
* yenta.c forces a secondary latency timer of 176.
* Copy that behaviour here.
@@ -936,43 +973,24 @@ 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->subordinate > max) &&
- (parent->subordinate <= 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.
*/
+ shrink_size = child->subordinate - max;
child->subordinate = 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)
+ pci_bus_shrink_top(bus, shrink_size, parent_res);
+
+ if (old_max > max)
+ max = old_max;
}

sprintf(child->name,
--
1.7.7