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    Subject[PATCH 19/24] PCI: Allocate bus range instead of use max blindly
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    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 5c031f0..f22a209 100644
    --- a/drivers/pci/probe.c
    +++ b/drivers/pci/probe.c
    @@ -839,10 +839,11 @@ 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;
    @@ -859,10 +860,16 @@ 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) */
    @@ -895,6 +902,8 @@ 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);
    @@ -907,6 +916,11 @@ 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
    @@ -923,20 +937,43 @@ 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.
    @@ -967,43 +1004,24 @@ 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


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