On Friday, June 28, 2013 04:34:21 PM Yinghai Lu wrote: > On Fri, Jun 28, 2013 at 3:53 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > The ACPI dock driver uses register_acpi_bus_notifier() which > > installs a notifier triggered globally for all system notifications. > > That first of all is inefficient, because the dock driver is only > > interested in notifications associated with the devices it handles, > > but it has to handle all system notifies for all devices. Moreover, > > it does that even if no docking stations are present in the system > > (CONFIG_ACPI_DOCK set is sufficient for that to happen). Besides, > > that is inconvenient, because it requires the driver to do extra work > > for each notification to find the target dock station object. > > > > For these reasons, rework the dock driver to install a notify > > handler individually for each dock station in the system using > > acpi_install_notify_handler(). This allows the dock station > > object to be passed directly to the notify handler and makes it > > possible to simplify the dock driver quite a bit. It also > > reduces the overhead related to the handling of all system > > notifies when CONFIG_ACPI_DOCK is set. > > original change to use register_acpi_bus_notifier, have two assumption > 1. two dock_station will have same handle. Well, that would mean that dock_add() might be called twice for the same handle and I don't see how that's possible. Moreover, even if that were possible, the loop in acpi_dock_notifier_call() would break after finding the *first* matching handle anyway, so acpi_dock_deferred_cb() wouldn't be called for the second dock station with the same handle, if there were two. > 2. acpi subsystem: non root acpi device only can have one system > notifier installed. No, that limitation is long gone. We removed it when we were working on ACPI wakeup support for runtime PM. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
