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Subject[PATCH 1/1] PCI: Coalesce host bridge contiguous apertures without sorting
Date
Commit 65db04053efe ("PCI: Coalesce host bridge contiguous apertures")
sorts the resources by address so the resources can be swapped.

Before:
PCI host bridge to bus 0002:00
pci_bus 0002:00: root bus resource [io 0x0000-0xffff]
pci_bus 0002:00: root bus resource [mem 0xd80000000-0xdffffffff] (bus address [0x80000000-0xffffffff])
pci_bus 0002:00: root bus resource [mem 0xc0ee00000-0xc0eefffff] (bus address [0x00000000-0x000fffff])

And after:
PCI host bridge to bus 0002:00
pci_bus 0002:00: root bus resource [io 0x0000-0xffff]
pci_bus 0002:00: root bus resource [mem 0xc0ee00000-0xc0eefffff] (bus address [0x00000000-0x000fffff])
pci_bus 0002:00: root bus resource [mem 0xd80000000-0xdffffffff] (bus address [0x80000000-0xffffffff])

However, the sorted resources make NVMe stops working on QEMU ppc:sam460ex.

Resources in the original issue are already in ascending order:
pci_bus 0000:00: root bus resource [mem 0x10020200000-0x100303fffff window]
pci_bus 0000:00: root bus resource [mem 0x10030400000-0x100401fffff window]

So remove the sorting part to resolve the issue.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 65db04053efe ("PCI: Coalesce host bridge contiguous apertures")
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
drivers/pci/probe.c | 31 +++++++++++++++++++++++++++----
1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 79177ac37880..5de157600466 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -877,11 +877,11 @@ static void pci_set_bus_msi_domain(struct pci_bus *bus)
static int pci_register_host_bridge(struct pci_host_bridge *bridge)
{
struct device *parent = bridge->dev.parent;
- struct resource_entry *window, *n;
+ struct resource_entry *window, *next, *n;
struct pci_bus *bus, *b;
- resource_size_t offset;
+ resource_size_t offset, next_offset;
LIST_HEAD(resources);
- struct resource *res;
+ struct resource *res, *next_res;
char addr[64], *fmt;
const char *name;
int err;
@@ -961,11 +961,34 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
if (nr_node_ids > 1 && pcibus_to_node(bus) == NUMA_NO_NODE)
dev_warn(&bus->dev, "Unknown NUMA node; performance will be reduced\n");

+ /* Coalesce contiguous windows */
+ resource_list_for_each_entry_safe(window, n, &resources) {
+ if (list_is_last(&window->node, &resources))
+ break;
+
+ next = list_next_entry(window, node);
+ offset = window->offset;
+ res = window->res;
+ next_offset = next->offset;
+ next_res = next->res;
+
+ if (res->flags != next_res->flags || offset != next_offset)
+ continue;
+
+ if (res->end + 1 == next_res->start) {
+ next_res->start = res->start;
+ res->flags = res->start = res->end = 0;
+ }
+ }
+
/* Add initial resources to the bus */
resource_list_for_each_entry_safe(window, n, &resources) {
- list_move_tail(&window->node, &bridge->windows);
offset = window->offset;
res = window->res;
+ if (!res->end)
+ continue;
+
+ list_move_tail(&window->node, &bridge->windows);

if (res->flags & IORESOURCE_BUS)
pci_bus_insert_busn_res(bus, bus->number, res->end);
--
2.31.1
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