Subject: [PATCH 3/4] pci: Do not auto-enable PCI reallocation when _DSM #5 returns 0

From: Benjamin Herrenschmidt <[email-masked]>
Date: Sat, 15 Jun 2019 10:23:58 +1000

This prevents auto-enabling of bridges reallocation when the FW tells
us that the initial configuration must be preserved for a given host
bridge.

Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
---
 drivers/pci/setup-bus.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 0cdd5ff389de..049a5602b942 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1684,10 +1684,16 @@ static enum enable_type pci_realloc_detect(struct pci_bus *bus,
 					   enum enable_type enable_local)
 {
 	bool unassigned = false;
+	struct pci_host_bridge *hb;
 
 	if (enable_local != undefined)
 		return enable_local;
 
+	/* Don't realloc if ACPI tells us not to */
+	hb = pci_find_host_bridge(bus);
+	if (hb->preserve_config)
+		return auto_disabled;
+
 	pci_walk_bus(bus, iov_resources_unassigned, &unassigned);
 	if (unassigned)
 		return auto_enabled;
-- 
2.17.1

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