[PATCH 4.4 45/57] Revert "PCI: PM: Do not read power state in pci_enable_device_flags()"
From: Sasha Levin <sashal@kernel.org>
Date: 2021-06-28 15:28:41
Also in:
lkml
Subsystem:
pci subsystem, the rest · Maintainers:
Bjorn Helgaas, Linus Torvalds
From: "Rafael J. Wysocki" <redacted>
[ Upstream commit 4d6035f9bf4ea12776322746a216e856dfe46698 ]
Revert commit 4514d991d992 ("PCI: PM: Do not read power state in
pci_enable_device_flags()") that is reported to cause PCI device
initialization issues on some systems.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=213481
Link: https://lore.kernel.org/linux-acpi/YNDoGICcg0V8HhpQ@eldamar.lan (local)
Reported-by: Michael <redacted>
Reported-by: Salvatore Bonaccorso <redacted>
Fixes: 4514d991d992 ("PCI: PM: Do not read power state in pci_enable_device_flags()")
Signed-off-by: Rafael J. Wysocki <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pci/pci.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 22e8172f373d..b7f65fc54dc2 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c@@ -1328,11 +1328,21 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) int err; int i, bars = 0; - if (atomic_inc_return(&dev->enable_cnt) > 1) { - pci_update_current_state(dev, dev->current_state); - return 0; /* already enabled */ + /* + * Power state could be unknown at this point, either due to a fresh + * boot or a device removal call. So get the current power state + * so that things like MSI message writing will behave as expected + * (e.g. if the device really is in D0 at enable time). + */ + if (dev->pm_cap) { + u16 pmcsr; + pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); + dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK); } + if (atomic_inc_return(&dev->enable_cnt) > 1) + return 0; /* already enabled */ + bridge = pci_upstream_bridge(dev); if (bridge) pci_enable_bridge(bridge);
--
2.30.2