On 06/22/2013 03:17 PM, Rafael J. Wysocki wrote:
On Saturday, June 22, 2013 02:11:14 PM Shuah Khan wrote:
Add a new interface get_pm_transition() to return pm_transition state. This interface is intended to be used from dev_pm_ops class and type suspend interfaces that call legacy pm ops driver suspend interfaces. Legacy suspend pm_ops take pm_message_t as a parameter.
e.g: drm_class_suspend() calls into driver suspend routines via drm_dev->driver->suspend(drm_dev, state).
Once drm_class_suspend() is converted to dev_pm_ops, it will no longer have access to pm_transition which it has to pass into driver legacy suspend calls. get_pm_transition() interface addresses this need.
That shouldn't be necessary because each transition has its own callback in strict dev_pm_ops.
Thanks, Rafael
Yes that is correct that there is no need pass in or know pm_transition with dev_pm_ops. The issue I am running into is the legacy pm_ops class suspend/resume routines call. In the example, I mentioned in my changelog, drm_class_suspend() calls legacy pm_ops and passes in state. It passes in the state to the driver legacy suspend routine. I have seen code paths in drivers that differentiate between PM_EVENT_FREEZE, PM_EVENT_SUSPEND, PM_EVENT_SLEEP etc.
I considered passing PM_EVENT_SUSPEND to drm_dev->driver->suspend(drm_dev, state) from drm_class_suspend() which would eliminate the need for this new interface. However, I am concerned about breaking driver legacy suspend routines that key of off the state to execute different code paths for PM_EVENT_FREEZE vs. PM_EVENT_SUSPEND. Suspend routines get called when state is is PM_EVENT_FREEZE based on my testing.
I would rather not add a new interface. Hoping you will have another idea on how to pass in the state to legacy suspend/resume without adding this new interface. My thinking is that this new interface is temporary measure until all of the legacy suspend routines get converted to dev_pm_ops and at the tile legacy interface gets removed, this new interface can go away as well.
thanks, -- Shuah
Shuah Khan, Linux Kernel Developer - Open Source Group Samsung Research America (Silicon Valley) shuah.kh@samsung.com | (970) 672-0658