On Sunday 24 June 2007, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rjw@xxxxxxx> > > Some drivers may need to use ACPI to determine the low power states in which > to place their devices, but to provide the drivers with this information the > ACPI core needs to know what sleep state the system is going to enter. It also needs to export that to things like the ACPI-to-PCI glue code. So it would be good if you defined the missing routine now, saving the effort of patching it in later: int acpi_get_target_sleep_state(void); It doesn't need EXPORT_SYMBOL(). > Namely, the device's state should not be too high power for given system sleep > state and, if the device is supposed to be able to wake up the system, its state > should not be too low power for the wake up to be possible). However, > pm_ops->prepare() is only called after the drivers' .suspend() callbacks have > been executed, That's a critical point that should show up in your doc updates. > so we need an additional means to pass the information of the > target system sleep state to the ACPI core. For this purpose, we can introduce > an additional member function in 'struct pm_ops'. > > Additionally, the at91 platform code incorrectly assumes that pm_ops->prepare() > will be called before devices are suspended and uses it for setting the target > system sleep state, so pm_ops->prepare() should to be replaced with the new > operation, pm_ops->set_target(), for this architecture. That was originally correct ... but as you pointed out, the semantics there changed in RC5. Which means this patch is a *BUGFIX*, preventing what would otherwise be a regression in 2.6.22 ... and so it should be merged for RC6 or so. Another way to describe the changes is that set_target() now does what prepare() used to do, while prepare() serves a new role. A role which still needs to be well-described in the documentation you provided, by the way... it seems to do whatever needs to be done after devices suspend but before nonboot CPUs are disabled. - Dave _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
