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PCI / PM: Allow runtime PM without callback functions

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a9c8088c79 ("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
6cbf82148f ("PCI PM: Run-time callbacks for PCI bus type").

On the other hand, a similar change was done to generic runtime PM
callbacks in 05aa55dddb ("PM / Runtime: Lenient generic runtime pm
callbacks").

Fixes: a9c8088c79 ("i2c: i801: Don't restore config registers on runtime PM")
Reported-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: stable@vger.kernel.org	# v4.18+
This commit is contained in:
Jarkko Nikula 2018-10-23 14:45:52 +03:00 committed by Bjorn Helgaas
parent 651022382c
commit c5eb119007
1 changed files with 12 additions and 15 deletions
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27
drivers/pci/pci-driver.c
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@ -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);
else
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;