[PATCH v2 18/24] PCI: Use pbus_select_window() in space available checker

Ilpo Järvinen
2025-08-29T13:13:35Z

pbus_upstream_space_available() figures out the upstream bridge window
resources on its own. Migrate it to use pbus_select_window().

Note: pbus_select_window() -> pbus_select_window_for_type() calls
find_bus_resource_of_type() for root bus, which does not do parent check
similar to what pbus_upstream_space_available() did earlier, but the
difference does not matter because pbus_upstream_space_available() itself
stops when it encounters the root bus.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
drivers/pci/setup-bus.c | 65 ++++++++++++++++++++---------------------
1 file changed, 32 insertions(+), 33 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 5ec446c2b779..865bacae9cac 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1221,19 +1221,20 @@ static inline resource_size_t calculate_mem_align(resource_size_t *aligns,
/**
* pbus_upstream_space_available - Check no upstream resource limits allocation
* @bus: The bus
- * @mask: Mask the resource flag, then compare it with type
- * @type: The type of resource from bridge
+ * @res: The resource to help select the correct bridge window
* @size: The size required from the bridge window
* @align: Required alignment for the resource
*
- * Checks that @size can fit inside the upstream bridge resources that are
- * already assigned.
+ * Check that @size can fit inside the upstream bridge resources that are
+ * already assigned. Select the upstream bridge window based on the type of
+ * @res.
*
* Return: %true if enough space is available on all assigned upstream
* resources.
*/
-static bool pbus_upstream_space_available(struct pci_bus *bus, unsigned long mask,
- unsigned long type, resource_size_t size,
+static bool pbus_upstream_space_available(struct pci_bus *bus,
+ struct resource *res,
+ resource_size_t size,
resource_size_t align)
{
struct resource_constraint constraint = {
@@ -1241,39 +1242,39 @@ static bool pbus_upstream_space_available(struct pci_bus *bus, unsigned long mas
.align = align,
};
struct pci_bus *downstream = bus;
- struct resource *res;

while ((bus = bus->parent)) {
if (pci_is_root_bus(bus))
break;

- pci_bus_for_each_resource(bus, res) {
- if (!res || !res->parent || (res->flags & mask) != type)
- continue;
-
- if (resource_size(res) >= size) {
- struct resource gap = {};
+ res = pbus_select_window(bus, res);
+ if (!res)
+ return false;
+ if (!res->parent)
+ continue;

- if (find_resource_space(res, &gap, size, &constraint) == 0) {
- gap.flags = type;
- pci_dbg(bus->self,
- "Assigned bridge window %pR to %pR free space at %pR\n",
- res, &bus->busn_res, &gap);
- return true;
- }
- }
+ if (resource_size(res) >= size) {
+ struct resource gap = {};

- if (bus->self) {
- pci_info(bus->self,
- "Assigned bridge window %pR to %pR cannot fit 0x%llx required for %s bridging to %pR\n",
- res, &bus->busn_res,
- (unsigned long long)size,
- pci_name(downstream->self),
- &downstream->busn_res);
+ if (find_resource_space(res, &gap, size, &constraint) == 0) {
+ gap.flags = res->flags;
+ pci_dbg(bus->self,
+ "Assigned bridge window %pR to %pR free space at %pR\n",
+ res, &bus->busn_res, &gap);
+ return true;
}
+ }

- return false;
+ if (bus->self) {
+ pci_info(bus->self,
+ "Assigned bridge window %pR to %pR cannot fit 0x%llx required for %s bridging to %pR\n",
+ res, &bus->busn_res,
+ (unsigned long long)size,
+ pci_name(downstream->self),
+ &downstream->busn_res);
}
+
+ return false;
}

return true;
@@ -1395,8 +1396,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
b_res->flags &= ~IORESOURCE_DISABLED;

if (bus->self && size0 &&
- !pbus_upstream_space_available(bus, mask | IORESOURCE_PREFETCH, type,
- size0, min_align)) {
+ !pbus_upstream_space_available(bus, b_res, size0, min_align)) {
relaxed_align = 1ULL << (max_order + __ffs(SZ_1M));
relaxed_align = max(relaxed_align, win_align);
min_align = min(min_align, relaxed_align);
@@ -1411,8 +1411,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
resource_size(b_res), add_align);

if (bus->self && size1 &&
- !pbus_upstream_space_available(bus, mask | IORESOURCE_PREFETCH, type,
- size1, add_align)) {
+ !pbus_upstream_space_available(bus, b_res, size1, add_align)) {
relaxed_align = 1ULL << (max_order + __ffs(SZ_1M));
relaxed_align = max(relaxed_align, win_align);
min_align = min(min_align, relaxed_align);
--
2.39.5