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Subject[PATCH v2 6/7] PCI/PM: warn about incomplete actions in ->runtime_suspend() callback
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Documentation/power/pci.txt says:
| It is expected that the device driver's pm->runtime_suspend() callback will
| not attempt to prepare the device for signaling wakeup or to put it into a
| low-power state. The driver ought to leave these tasks to the PCI subsystem
| that has all of the information necessary to perform them.

After commit 42eca2302146fed51335b95128e949ee6f54478f
("PCI: Don't touch card regs after runtime suspend D3")
| If the driver takes care of state saving, don't touch any registers on it.
pci_pm_runtime_suspend() thinks if state has been saved by ->runtime_suspend()
that means device alredy prepared for wakeup and probably no longer accessible.

Thus driver must either do all actions or leave all these tasks to PCI subsystem.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
---
drivers/pci/pci-driver.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index f9aa311..2b0ff9a 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -1009,12 +1009,19 @@ static int pci_pm_runtime_suspend(struct device *dev)
return 0;
}

- if (!pci_dev->state_saved) {
- pci_save_state(pci_dev);
- pci_finish_runtime_suspend(pci_dev);
+ if (pci_dev->state_saved) {
+ WARN_ONCE(pci_dev->current_state == prev,
+ "PCI PM: Power state of device not changed by %pF\n",
+ pm->runtime_suspend);
+ WARN_ONCE(pci_dev_run_wake(pci_dev) &&
+ !pci_dev->wakeup_prepared,
+ "PCI PM: Waking of device not configured by %pF\n",
+ pm->runtime_suspend);
+ return 0;
}

- return 0;
+ pci_save_state(pci_dev);
+ return pci_finish_runtime_suspend(pci_dev);
}

static int pci_pm_runtime_resume(struct device *dev)


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