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PCI/PM: Only read PCI_PM_CTRL register when available

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commit 5694ba13b004eea683c6d4faeb6d6e7a9636bda0 upstream.

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: e200904b27 ("PCI/PM: Split pci_power_up()")
Link: https://lore.kernel.org/r/20230824013738.1894965-1-chenfeiyang@loongson.cn
Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: stable@vger.kernel.org	# v5.19+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Feiyang Chen 2023-08-24 09:37:38 +08:00 committed by Greg Kroah-Hartman
parent 223fc53520
commit e95e31a860
1 changed files with 9 additions and 4 deletions
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13
drivers/pci/pci.c
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@ -1193,6 +1193,10 @@ 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)
{
@ -1209,9 +1213,6 @@ int pci_power_up(struct pci_dev *dev)
else
dev->current_state = state;
if (state == PCI_D0)
return 0;
return -EIO;
}
@ -1269,8 +1270,12 @@ 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;