PM: runtime: Document that force_suspend() is incompatible with SMART_SUSPEND

pm_runtime_force_suspend() cannot be used with DPM_FLAG_SMART_SUSPEND, so
note this in the kerneldoc.

If DPM_FLAG_SMART_SUSPEND is set and the PM core cannot skip system resume
it will call pm_runtime_active() on the driver. This can lead to an
inconsistent state where:

  pm_runtime_force_suspend() called ->runtime_suspend

but

  device_resume_noirq() called pm_runtime_set_active()

This leaves the driver actually suspended but marked as active.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Richard Fitzgerald
2022-12-13 15:54:48 +00:00
committed by Rafael J. Wysocki
parent b7bfaa761d
commit 450316dc4f

View File

@@ -1864,6 +1864,10 @@ static bool pm_runtime_need_not_resume(struct device *dev)
* sure the device is put into low power state and it should only be used during
* system-wide PM transitions to sleep states. It assumes that the analogous
* pm_runtime_force_resume() will be used to resume the device.
*
* Do not use with DPM_FLAG_SMART_SUSPEND as this can lead to an inconsistent
* state where this function has called the ->runtime_suspend callback but the
* PM core marks the driver as runtime active.
*/
int pm_runtime_force_suspend(struct device *dev)
{