[Matthew Garrett <mjg59@xxxxxxxxxxxxx>] > > Ok, so let's think about this differently. What we want is simply for > drivers to be able to block an automatic suspend. For performance > reasons we want to keep track of this state without calling into the > entire driver tree. Now that the userspace API can automatically clean > up after itself, why is this not just a simple counter? Kernel API would > be something like: > > (input arrives) > inhibit_suspend(); > (input queue is emptied) > uninhibit_suspend(); > > perhaps using the device struct or something as a token for debug > purposes. Userland ABI would then be a single /dev/inhibit_suspend, > with the counter being bumped each time an application opens it. It'll > automatically be dropped if the application exits without cleaning up. > > This seems simpler and also avoids any arguments about the naming > scheme. What am I missing? If we can enable keeping stats (probably as a config option that defaults off) to help answer the "battery life is down 20% in this build, are we preventing suspend more than before?" question, this seems like a reasonable direction to me. For the case where somebody wants to release the hold on suspend after a timer expiration, that can be built on top of this, so that's covered. I think the "what happens when a process crashes and its suspend inhibits are released" issue still needs some thought -- if say a background/service process crashes while holding a lock we want to have the process be able to be restarted by init or whatnot without having to wait for some other activity. This is a real example we ran into in the past -- telephony process crashes and the device doesn't get back on the network until the user presses a key, an alarm fires, etc. I suspect this is more sparse than Arve is hoping for, and maybe I've missed some obvious concern he has. Brian _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
