Commit c5eb1190 authored by Jarkko Nikula's avatar Jarkko Nikula Committed by Bjorn Helgaas
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PCI / PM: Allow runtime PM without callback functions

a9c8088c ("i2c: i801: Don't restore config registers on runtime PM")
nullified the runtime PM suspend/resume callback pointers while keeping the
runtime PM enabled.

This caused the SMBus PCI device to stay in D0 with
/sys/devices/.../power/runtime_status showing "error" when the runtime PM
framework attempted to autosuspend the device.  This is due to PCI bus
runtime PM, which checks for driver runtime PM callbacks and returns
-ENOSYS if they are not set.

Since i2c-i801.c doesn't need to do anything device-specific for runtime
PM, Jean Delvare proposed this be fixed in the PCI core rather than adding
dummy runtime PM callback functions in the PCI drivers.

Change pci_pm_runtime_suspend()/pci_pm_runtime_resume() so they allow
changing the PCI device power state during runtime PM transitions even if
the driver supplies no runtime PM callbacks.

This fixes the runtime PM regression on i2c-i801.c.

It is not obvious why the code previously required the runtime PM
callbacks.  The test has been there since the code was introduced by
6cbf8214 ("PCI PM: Run-time callbacks for PCI bus type").

On the other hand, a similar change was done to generic runtime PM
callbacks in 05aa55dd ("PM / Runtime: Lenient generic runtime pm

Fixes: a9c8088c

 ("i2c: i801: Don't restore config registers on runtime PM")
Reported-by: default avatarMika Westerberg <>
Signed-off-by: default avatarJarkko Nikula <>
Signed-off-by: default avatarBjorn Helgaas <>
Reviewed-by: default avatarJean Delvare <>
Reviewed-by: default avatarRafael J. Wysocki <>
Cc:	# v4.18+
parent 65102238
......@@ -1251,30 +1251,29 @@ static int pci_pm_runtime_suspend(struct device *dev)
return 0;
if (!pm || !pm->runtime_suspend)
return -ENOSYS;
pci_dev->state_saved = false;
error = pm->runtime_suspend(dev);
if (error) {
if (pm && pm->runtime_suspend) {
error = pm->runtime_suspend(dev);
* -EBUSY and -EAGAIN is used to request the runtime PM core
* to schedule a new suspend, so log the event only with debug
* log level.
if (error == -EBUSY || error == -EAGAIN)
if (error == -EBUSY || error == -EAGAIN) {
dev_dbg(dev, "can't suspend now (%pf returned %d)\n",
pm->runtime_suspend, error);
return error;
} else if (error) {
dev_err(dev, "can't suspend (%pf returned %d)\n",
pm->runtime_suspend, error);
return error;
return error;
pci_fixup_device(pci_fixup_suspend, pci_dev);
if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0
if (pm && pm->runtime_suspend
&& !pci_dev->state_saved && pci_dev->current_state != PCI_D0
&& pci_dev->current_state != PCI_UNKNOWN) {
WARN_ONCE(pci_dev->current_state != prev,
"PCI PM: State of device not saved by %pF\n",
......@@ -1292,7 +1291,7 @@ static int pci_pm_runtime_suspend(struct device *dev)
static int pci_pm_runtime_resume(struct device *dev)
int rc;
int rc = 0;
struct pci_dev *pci_dev = to_pci_dev(dev);
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
......@@ -1306,14 +1305,12 @@ static int pci_pm_runtime_resume(struct device *dev)
if (!pci_dev->driver)
return 0;
if (!pm || !pm->runtime_resume)
return -ENOSYS;
pci_fixup_device(pci_fixup_resume_early, pci_dev);
pci_enable_wake(pci_dev, PCI_D0, false);
pci_fixup_device(pci_fixup_resume, pci_dev);
rc = pm->runtime_resume(dev);
if (pm && pm->runtime_resume)
rc = pm->runtime_resume(dev);
pci_dev->runtime_d3cold = false;
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