Revert "PCI: PM: Do not read power state in pci_enable_device_flags()"

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
Reported-by: Michael <phyre@rogers.com>
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Fixes: 4514d991d992 ("PCI: PM: Do not read power state in pci_enable_device_flags()")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b717680..8d4ebe0 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1900,11 +1900,21 @@ 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);