On Friday, 21 of March 2008, Alan Stern wrote: > On Fri, 21 Mar 2008, Rafael J. Wysocki wrote: > > > The original code executed platform_pci_choose_state() first, if defined, and > > if that succeeded, it just returned the result. You put > > platform_pci_choose_state() under the switch(). :-) > > For FREEZE and QUIESCE, is there ever any reason to leave D0? No, but there's a reason to leave it for HIBERNATE and that's what my original comment was about. > These calls are documented as not requiring (and not desiring!) any change > in power level. Correct, but that's not the point. Is there any reason why pci_choose_state() should try to figure out what kind of operation is being performed by the driver and tailor its output to that? I don't think so. Rather, the driver should know what it's doing and either call pci_choose_state() or not. If the state of the device is not to be changed, there's no reason to call pci_choose_state() at all. My opinion is that drivers should only use pci_choose_state() if they _intend_ to change the state of the device and they should expect that the result may not depend on the 'state' argument passed to it, but on the target state set by the platform. [Note that with the new suspend/hibernation callbacks there won't be the pm_message_t argument to pass to pci_choose_state().] Now, we need to settle _what_ exactly pci_choose_state() is supposed to return, because it's not clear right now. Should that be the lowest power state in which the device can be in given system state (that's what platform_pci_choose_state() will return)? Or should that be the highest power state in which the device can be in given system state? Or anything else? Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
