From eb75a73d87fcb45666118135d7ee814c770312f8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 8 Aug 2024 15:17:07 +0300 Subject: [PATCH] PCI: Wait for Link before restoring Downstream Buses MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit BugLink: https://bugs.launchpad.net/bugs/2089340 [ Upstream commit 3e40aa29d47e231a54640addf6a09c1f64c5b63f ] __pci_reset_bus() calls pci_bridge_secondary_bus_reset() to perform the reset and also waits for the Secondary Bus to become again accessible. __pci_reset_bus() then calls pci_bus_restore_locked() that restores the PCI devices connected to the bus, and if necessary, recursively restores also the subordinate buses and their devices. The logic in pci_bus_restore_locked() does not take into account that after restoring a device on one level, there might be another Link Downstream that can only start to come up after restore has been performed for its Downstream Port device. That is, the Link may require additional wait until it becomes accessible. Similarly, pci_slot_restore_locked() lacks wait. Amend pci_bus_restore_locked() and pci_slot_restore_locked() to wait for the Secondary Bus before recursively performing the restore of that bus. Fixes: 090a3c5322e9 ("PCI: Add pci_reset_slot() and pci_reset_bus()") Link: https://lore.kernel.org/r/20240808121708.2523-1-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Signed-off-by: Sasha Levin Signed-off-by: Portia Stephens Signed-off-by: Stefan Bader --- drivers/pci/pci.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 321851a76371..db1969296219 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5883,8 +5883,10 @@ static void pci_bus_restore_locked(struct pci_bus *bus) list_for_each_entry(dev, &bus->devices, bus_list) { pci_dev_restore(dev); - if (dev->subordinate) + if (dev->subordinate) { + pci_bridge_wait_for_secondary_bus(dev, "bus reset"); pci_bus_restore_locked(dev->subordinate); + } } } @@ -5918,8 +5920,10 @@ static void pci_slot_restore_locked(struct pci_slot *slot) if (!dev->slot || dev->slot != slot) continue; pci_dev_restore(dev); - if (dev->subordinate) + if (dev->subordinate) { + pci_bridge_wait_for_secondary_bus(dev, "slot reset"); pci_bus_restore_locked(dev->subordinate); + } } }