From: Feiyang Chen <chenfeiyang@xxxxxxxxxxx>
For a device with no Power Management Capability, pci_power_up() previously
returned 0 (success) if the platform was able to put the device in D0,
which led to pci_set_full_power_state() trying to read PCI_PM_CTRL, even
though it doesn't exist.
Since dev->pm_cap == 0 in this case, pci_set_full_power_state() actually
read the wrong register, interpreted it as PCI_PM_CTRL, and corrupted
dev->current_state. This led to messages like this in some cases:
pci 0000:01:00.0: Refused to change power state from D3hot to D0
To prevent this, make pci_power_up() always return a negative failure code
if the device lacks a Power Management Capability, even if non-PCI platform
power management has been able to put the device in D0. The failure will
prevent pci_set_full_power_state() from trying to access PCI_PM_CTRL.
Fixes: e200904b275c ("PCI/PM: Split pci_power_up()")
Link: https://lore.kernel.org/r/20230824013738.1894965-1-chenfeiyang@xxxxxxxxxxx
Signed-off-by: Feiyang Chen <chenfeiyang@xxxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Signed-off-by: Yanteng Si <siyanteng@xxxxxxxxxxx>
Reviewed-by: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.19+
---
v4:
Modify commit messages.
BTW, Feiyang went on vacation, I will continue this patch.
drivers/pci/pci.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index f59f3c1c9869..59c01d68c6d5 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1226,6 +1226,10 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
*
* On success, return 0 or 1, depending on whether or not it is necessary to
* restore the device's BARs subsequently (1 is returned in that case).
+ *
+ * On failure, return a negative error code. Always return failure if @dev
+ * lacks a Power Management Capability, even if the platform was able to
+ * put the device in D0 via non-PCI means.
*/
int pci_power_up(struct pci_dev *dev)
{
@@ -1242,9 +1246,6 @@ int pci_power_up(struct pci_dev *dev)
else
dev->current_state = state;
- if (state == PCI_D0)
- return 0;
-
return -EIO;
}
@@ -1302,8 +1303,12 @@ static int pci_set_full_power_state(struct pci_dev *dev)
int ret;
ret = pci_power_up(dev);
- if (ret < 0)
+ if (ret < 0) {
+ if (dev->current_state == PCI_D0)
+ return 0;
+
return ret;
+ }
pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
dev->current_state = pmcsr & PCI_PM_CTRL_STATE_MASK;
--
2.31.4
