linux-kernel - [PATCH 1/2] PCI: Setup bridge resources earlier

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Message-Id: <20250924134228.1663-2-ilpo.jarvinen@linux.intel.com>
Date: Wed, 24 Sep 2025 16:42:27 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: linux-pci@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Krzysztof Wilczyński <kw@...ux.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	linux-kernel@...r.kernel.org
Cc: Lucas De Marchi <lucas.demarchi@...el.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 1/2] PCI: Setup bridge resources earlier

Bridge windows are read twice from PCI Config Space, the first read is
made from pci_read_bridge_windows() which does not setup the device's
resources. It causes problems down the road as child resources of the
bridge cannot check whether they reside within the bridge window or
not.

Setup the bridge windows already in pci_read_bridge_windows().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---

I'm not entirely sure what is the reason why the bridge resources were
not set up by pci_read_bridge_windows(). So far I'm yet to run into any
issues because of that but perhaps there's some good reason for that
I'm not aware of?

This patch likely allows also removing pci_bridge_check_ranges() but I'm
yet to confirm that.

 drivers/pci/probe.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index f41128f91ca7..7f9da8c41620 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -524,10 +524,14 @@ static void pci_read_bridge_windows(struct pci_dev *bridge)
 	}
 	if (io) {
 		bridge->io_window = 1;
-		pci_read_bridge_io(bridge, &res, true);
+		pci_read_bridge_io(bridge,
+				   pci_resource_n(bridge, PCI_BRIDGE_IO_WINDOW),
+				   true);
 	}
 
-	pci_read_bridge_mmio(bridge, &res, true);
+	pci_read_bridge_mmio(bridge,
+			     pci_resource_n(bridge, PCI_BRIDGE_MEM_WINDOW),
+			     true);
 
 	/*
 	 * DECchip 21050 pass 2 errata: the bridge may miss an address
@@ -565,7 +569,10 @@ static void pci_read_bridge_windows(struct pci_dev *bridge)
 			bridge->pref_64_window = 1;
 	}
 
-	pci_read_bridge_mmio_pref(bridge, &res, true);
+	pci_read_bridge_mmio_pref(bridge,
+				  pci_resource_n(bridge,
+						 PCI_BRIDGE_PREF_MEM_WINDOW),
+				  true);
 }
 
 void pci_read_bridge_bases(struct pci_bus *child)
-- 
2.39.5