Rafael,
Concluding, it seems to me that the "restore" code path is correct, but the "hibernate" code path is not and should be reworked. Also, it seems that acpi_pm_prepare() and acpi_pm_enter() should be fixed for the s2ram case either (_PTS should be executed after device_suspend() and _GTS should be executed in acpi_pm_enter(), right before the transition is completed).
Current implementation is not fully up-to spec, so we may try to get it closer to, I agree.
When we restore the system state from a hibernation image, the "boot kernel" is first started. It loads the image into memory, calls device_suspend(PMSG_PRETHAW), suspends sysdevs etc., and replaces itself with the "resumed kernel". It doesn't call acpi_pm_prepare(), which I think is right, because it doesn't want to start any power transition, not even a fake one. Now, the "resumed kernel" takes control, resumes sysdevs and calls
Currently call to prepare() is needed to stop ACPI devices to send GPEs to ACPI drivers. If you remove it, Acer laptops will resume without ACPI interrupt at all (with all problems from it).
acpi_pm_finish(), which seems to be about OK, except that I'm not sure if _BFS should be executed in that case (the ACPI spec seems to assume that the hibernation image will be loaded into memory by a boot loader).
Next, we suspend sysdevs etc., and create the memory snapshot. We want to be able to save it, so w call acpi_pm_finish(), which causes _BFS and _WAK to be executed *after* _GTS, which is clearly against the spec (might this be the reason why (7) is sometimes necessary?). Moreover, calling _BFS at this stage makes no sense, IMHO, since there hasn't been any transition (the system has not slept). What I think we should do at this point is to execute _WAK only, which means "power transition aborted" to the firmware, and continue with device_resume().
But I don't get your idea about executing _finish() between _prepare() and _enter()... _finish is executed only if _prepare() fails, so we are rolling back, or it is executed after we loaded the image and transfered execution to it, so again -- we are going from _prepare() state to running state... Regards, Alex. _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
