From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com
stable inclusion from linux-4.19.207 commit 6d941bd6366a08bf5c660dbd4f8345427d56aefe
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[ Upstream commit 14858dcc3b3587f4bb5c48e130ee7d68fc2b0a29 ]
Updating the current_state field of struct pci_dev the way it is done in pci_enable_device_flags() before calling do_pci_enable_device() may not work. For example, if the given PCI device depends on an ACPI power resource whose _STA method initially returns 0 ("off"), but the config space of the PCI device is accessible and the power state retrieved from the PCI_PM_CTRL register is D0, the current_state field in the struct pci_dev representing that device will get out of sync with the power.state of its ACPI companion object and that will lead to power management issues going forward.
To avoid such issues, make pci_enable_device_flags() call pci_update_current_state() which takes ACPI device power management into account, if present, to retrieve the current power state of the device.
Link: https://lore.kernel.org/lkml/20210314000439.3138941-1-luzmaximilian@gmail.co... Reported-by: Maximilian Luz luzmaximilian@gmail.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Tested-by: Maximilian Luz luzmaximilian@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/pci/pci.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 921b410e315c9..48ff2c1084756 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1663,11 +1663,7 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) * 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); - } + pci_update_current_state(dev, dev->current_state);
if (atomic_inc_return(&dev->enable_cnt) > 1) return 0; /* already enabled */