On Monday, 25 June 2007 04:11, David Brownell wrote: > 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(). I'd rather like to add this as a separate patch in the same series. Will do. > > 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. Yes, will add that. > > 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. In that case I'd separate the addition of set_target() and the at91 from the rest of the series and push it to Andrew ASAP (there's a little time left before 2.6.22, it seems). > 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. Yes, exactly. I have the updated series of patches almost ready. I'll send it in a new thread in a while. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
