==========================================================================
Here is what happens when an Intel Gigabit ET2 quad port server adapter
is hot-added:
pci 0000:39:00.0: BAR 14: assigned [mem 0x53300000-0x6a0fffff]
^^^^^^^^^^
pci 0000:3a:01.0: BAR 14: assigned [mem 0x53400000-0x547fffff]
^^^^^^^^^^
The above shows that the downstream bridge (3a:01.0) window is aligned
to 2 MB instead of 1 MB as is the upstream bridge (39:00.0) window. The
remaining MMIO space (0x15a00000) is assigned to the hotplug bridge
(3a:04.0) but it fails:
pci 0000:3a:04.0: BAR 14: no space for [mem size 0x15a00000]
pci 0000:3a:04.0: BAR 14: failed to assign [mem size 0x15a00000]
==========================================================================
Rewrite pci_bus_distribute_available_resources() to better handle
bridges with different resource alignment requirements. Pass more
details arguments recursively to track the resource start and end
addresses relative to the initial hotplug bridge. This is especially
useful for Thunderbolt with native PCI enumeration, enabling external
graphics cards and other devices with bridge alignment higher than
0x100000 bytes.
Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>
---
drivers/pci/setup-bus.c | 164 ++++++++++++++++++++--------------------
1 file changed, 83 insertions(+), 81 deletions(-)
@@ -1839,10 +1839,10 @@ static void extend_bridge_window(struct pci_dev *bridge, struct resource *res,
}
static void pci_bus_distribute_available_resources(struct pci_bus *bus,
- struct list_head *add_list, resource_size_t available_io,
- resource_size_t available_mmio, resource_size_t available_mmio_pref)
+ struct list_head *add_list, struct resource io,
+ struct resource mmio, struct resource mmio_pref)
{
- resource_size_t remaining_io, remaining_mmio, remaining_mmio_pref;
+ resource_size_t io_per_hp, mmio_per_hp, mmio_pref_per_hp, align;
unsigned int normal_bridges = 0, hotplug_bridges = 0;
struct resource *io_res, *mmio_res, *mmio_pref_res;
struct pci_dev *dev, *bridge = bus->self;
@@ -1852,25 +1852,32 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus,
mmio_pref_res = &bridge->resource[PCI_BRIDGE_RESOURCES + 2];
/*
- * Update additional resource list (add_list) to fill all the
- * extra resource space available for this port except the space
- * calculated in __pci_bus_size_bridges() which covers all the
- * devices currently connected to the port and below.
+ * The alignment of this bridge is yet to be considered, hence it must
+ * be done now before extending its bridge window. A single bridge
+ * might not be able to occupy the whole parent region if the alignment
+ * differs - for example, an external GPU at the end of a Thunderbolt
+ * daisy chain.
*/
- extend_bridge_window(bridge, io_res, add_list, available_io);
- extend_bridge_window(bridge, mmio_res, add_list, available_mmio);
- extend_bridge_window(bridge, mmio_pref_res, add_list,
- available_mmio_pref);
+ align = pci_resource_alignment(bridge, io_res);
+ if (!io_res->parent && align)
+ io.start = ALIGN(io.start, align);
+
+ align = pci_resource_alignment(bridge, mmio_res);
+ if (!mmio_res->parent && align)
+ mmio.start = ALIGN(mmio.start, align);
+
+ align = pci_resource_alignment(bridge, mmio_pref_res);
+ if (!mmio_pref_res->parent && align)
+ mmio_pref.start = ALIGN(mmio_pref.start, align);
/*
- * Calculate the total amount of extra resource space we can
- * pass to bridges below this one. This is basically the
- * extra space reduced by the minimal required space for the
- * non-hotplug bridges.
+ * Update the resources to fill as much remaining resource space in the
+ * parent bridge as possible, while considering alignment.
*/
- remaining_io = available_io;
- remaining_mmio = available_mmio;
- remaining_mmio_pref = available_mmio_pref;
+ extend_bridge_window(bridge, io_res, add_list, resource_size(&io));
+ extend_bridge_window(bridge, mmio_res, add_list, resource_size(&mmio));
+ extend_bridge_window(bridge, mmio_pref_res, add_list,
+ resource_size(&mmio_pref));
/*
* Calculate how many hotplug bridges and normal bridges there
@@ -1884,80 +1891,79 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus,
normal_bridges++;
}
+ /*
+ * There is only one bridge on the bus so it gets all possible
+ * resources which it can then distribute to the possible
+ * hotplug bridges below.
+ */
+ if (hotplug_bridges + normal_bridges == 1) {
+ dev = list_first_entry(&bus->devices, struct pci_dev, bus_list);
+ if (dev->subordinate)
+ pci_bus_distribute_available_resources(dev->subordinate,
+ add_list, io, mmio, mmio_pref);
+ return;
+ }
+
+ /*
+ * Reduce the available resource space by what the
+ * bridge and devices below it occupy.
+ */
for_each_pci_bridge(dev, bus) {
- const struct resource *res;
+ struct resource *res;
+ resource_size_t used_size;
if (dev->is_hotplug_bridge)
continue;
- /*
- * Reduce the available resource space by what the
- * bridge and devices below it occupy.
- */
res = &dev->resource[PCI_BRIDGE_RESOURCES + 0];
- if (!res->parent && available_io > resource_size(res))
- remaining_io -= resource_size(res);
+ align = pci_resource_alignment(dev, res);
+ align = align ? ALIGN(io.start, align) - io.start : 0;
+ used_size = align + resource_size(res);
+ if (!res->parent && used_size <= resource_size(&io))
+ io.start += used_size;
res = &dev->resource[PCI_BRIDGE_RESOURCES + 1];
- if (!res->parent && available_mmio > resource_size(res))
- remaining_mmio -= resource_size(res);
+ align = pci_resource_alignment(dev, res);
+ align = align ? ALIGN(mmio.start, align) - mmio.start : 0;
+ used_size = align + resource_size(res);
+ if (!res->parent && used_size <= resource_size(&mmio))
+ mmio.start += used_size;
res = &dev->resource[PCI_BRIDGE_RESOURCES + 2];
- if (!res->parent && available_mmio_pref > resource_size(res))
- remaining_mmio_pref -= resource_size(res);
+ align = pci_resource_alignment(dev, res);
+ align = align ? ALIGN(mmio_pref.start, align) -
+ mmio_pref.start : 0;
+ used_size = align + resource_size(res);
+ if (!res->parent && used_size <= resource_size(&mmio_pref))
+ mmio_pref.start += used_size;
}
- /*
- * There is only one bridge on the bus so it gets all available
- * resources which it can then distribute to the possible
- * hotplug bridges below.
- */
- if (hotplug_bridges + normal_bridges == 1) {
- dev = list_first_entry(&bus->devices, struct pci_dev, bus_list);
- if (dev->subordinate) {
- pci_bus_distribute_available_resources(dev->subordinate,
- add_list, available_io, available_mmio,
- available_mmio_pref);
- }
+ if (!hotplug_bridges)
return;
- }
/*
- * Go over devices on this bus and distribute the remaining
- * resource space between hotplug bridges.
+ * Distribute any remaining resources equally between
+ * the hotplug-capable downstream ports.
*/
- for_each_pci_bridge(dev, bus) {
- resource_size_t align, io, mmio, mmio_pref;
- struct pci_bus *b;
+ io_per_hp = div64_ul(resource_size(&io), hotplug_bridges);
+ mmio_per_hp = div64_ul(resource_size(&mmio), hotplug_bridges);
+ mmio_pref_per_hp = div64_ul(resource_size(&mmio_pref),
+ hotplug_bridges);
- b = dev->subordinate;
- if (!b || !dev->is_hotplug_bridge)
+ for_each_pci_bridge(dev, bus) {
+ if (!dev->subordinate || !dev->is_hotplug_bridge)
continue;
- /*
- * Distribute available extra resources equally between
- * hotplug-capable downstream ports taking alignment into
- * account.
- *
- * Here hotplug_bridges is always != 0.
- */
- align = pci_resource_alignment(bridge, io_res);
- io = div64_ul(available_io, hotplug_bridges);
- io = min(ALIGN(io, align), remaining_io);
- remaining_io -= io;
-
- align = pci_resource_alignment(bridge, mmio_res);
- mmio = div64_ul(available_mmio, hotplug_bridges);
- mmio = min(ALIGN(mmio, align), remaining_mmio);
- remaining_mmio -= mmio;
+ io.end = io.start + io_per_hp - 1;
+ mmio.end = mmio.start + mmio_per_hp - 1;
+ mmio_pref.end = mmio_pref.start + mmio_pref_per_hp - 1;
- align = pci_resource_alignment(bridge, mmio_pref_res);
- mmio_pref = div64_ul(available_mmio_pref, hotplug_bridges);
- mmio_pref = min(ALIGN(mmio_pref, align), remaining_mmio_pref);
- remaining_mmio_pref -= mmio_pref;
+ pci_bus_distribute_available_resources(dev->subordinate,
+ add_list, io, mmio, mmio_pref);
- pci_bus_distribute_available_resources(b, add_list, io, mmio,
- mmio_pref);
+ io.start = io.end + 1;
+ mmio.start = mmio.end + 1;
+ mmio_pref.start = mmio_pref.end + 1;
}
}
@@ -1965,22 +1971,18 @@ static void
pci_bridge_distribute_available_resources(struct pci_dev *bridge,
struct list_head *add_list)
{
- resource_size_t available_io, available_mmio, available_mmio_pref;
- const struct resource *res;
+ struct resource io_res, mmio_res, mmio_pref_res;
if (!bridge->is_hotplug_bridge)
return;
- /* Take the initial extra resources from the hotplug port */
- res = &bridge->resource[PCI_BRIDGE_RESOURCES + 0];
- available_io = resource_size(res);
- res = &bridge->resource[PCI_BRIDGE_RESOURCES + 1];
- available_mmio = resource_size(res);
- res = &bridge->resource[PCI_BRIDGE_RESOURCES + 2];
- available_mmio_pref = resource_size(res);
+ io_res = bridge->resource[PCI_BRIDGE_RESOURCES + 0];
+ mmio_res = bridge->resource[PCI_BRIDGE_RESOURCES + 1];
+ mmio_pref_res = bridge->resource[PCI_BRIDGE_RESOURCES + 2];
+ /* Take the initial extra resources from the hotplug port */
pci_bus_distribute_available_resources(bridge->subordinate,
- add_list, available_io, available_mmio, available_mmio_pref);
+ add_list, io_res, mmio_res, mmio_pref_res);
}
void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)