On Tue, Jun 16, 2015 at 01:17:29PM +0200, Lennart Poettering wrote: > On Tue, 16.06.15 10:14, Chris Wilson (chris@xxxxxxxxxxxxxxxxxx) wrote: > > > The biggest change here is 4.1 stopped forcing the probe from sysfs > > precisely because systemd was hitting them so often for illogical > > reasons (being docked depends on having the lid open and an > > external display connected!). To force the probe, you must do > > $ echo detect > /sys/class/drm/*/status > > The way people "dock" their laptops these days is apparently that > they plug in an external keyboard+mouse and a display, close the lid > and stash the laptop away somewhere. logind hence counts the displays > connected, and if its >= 2 it doesn't suspend the machine even if the > lid is closed. Before logind, GNOME implemented the very same > logic. It's hence hardly "illogical", it's just how this works... Note that a closed lid causes the internal panel to be reported as disconnected - it always has (with the exception of a module parameter to force otherwise to accommodate broken lid buttons). Using the number of connected displays is thus flawed. > > > We don't really depend on the userspace doing the reprobe, do we? On > > > resume, we reprobe the HPD capable connectors and schedule a poll for > > > the rest. Is it even possible the userspace sees unknown status for HPD > > > capable connectors on resume? Makes me wonder if there's something going > > > wrong with the hotplug irqs. > > > > The unknown status is much more likely after boot, iirc. Unknown is not > > a big problem because very, very few applications actually query the > > current value without doing a probe (basically the new sysfs entry and > > X during takeover). We simply have not been able to trust hotplug to > > allow us to cache connector status at any level. > > Well, logind does not probe right now. I was not aware one has to do > this. > > Is there any reason the kernel doesn't automatically probe the > connectors when userspace asks for it and would return "unknown" > otherwise? Probing is very slow and will cause flicker on some machines. > I can also implement a logic like that in logind, but then again, > maybe logind should leave the probing the connectors to X or the > kernel to figure out on their own? Yes. logind is only using the status to count the number of connected outputs, when it was probing I noticed because logind was using more CPU time during X startup/shutdown than X was itself. > Is the API of these files documented anywhere? The status is the first one we added a store attribute to, probably why we overlooked expanding the none existent documentation. We also have not documented the meaning of the reported string. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
