On Tue, Jun 06, 2017 at 12:22:09PM +0200, Benjamin Tissoires wrote: [...] > > This is because the aml table puts many Notify(LID, 0x80) in various > > control methods. > > And not one of them but multiple of them will be invoked by various OS > > drivers during suspend/resume period. > > I think this is not an isolated platform that will invoke multiple > > redundant "Notify(lid)". > > > > Fortunately, the lid state for the multiple notify(lid) should be same as > > the first "Notify(lid)". > > I suppose this is why SW_LID is invented, as it can really filter such > > redundant events. > > And user space finally can only see 1 "close" event. > > > > But unconditionally prepending "open" before all "close" events surely can > > break the logic by > > delivering multiple "close" events to the user space. > > That doesn't matter. What matters is the state of the switch, not the > event. So if user space receives (in case we marked the switch as not > reliable) several close events, all user space will do is realize that > the state is still closed and will act accordingly.
[...] > Again, we don't care if the "event" comes from ACPI, the driver itself or > user space (libinput). All that matters is the current state of the > input node switch, that needs to match the physical world at any time. as extra comment on those two: you cannot guarantee when e.g. libinput checks the state. it may start up after the kernel has updated the EV_SW state, it may close and re-open a device without notice (disabling a device in X has that effect for example). So the EV_SW/SW_LID events are nice to have, but we really rely on the *state* of the switch more than the events. Cheers, Peter _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
