On Tue, Mar 25, 2014 at 6:24 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Tue, Mar 25, 2014 at 6:53 AM, Dave Airlie <airlied@xxxxxxxxx> wrote: >> So with runtime pm on nouveau, if the card gets powered down, and then >> you access a connector via sysfs, >> >> drm_sysfs.c:status_show locks the connector and calls into the driver, >> the driver then does a runtime_get_sync, which causes resume to happen >> which causes modesetting to reset the mode, which tries to take all >> the locks, and it all deadlocks in a pile, >> >> Ideas to fix this, move the runtime_get_sync into the drm_sysfs code, >> or allow the drivers to provide their own status show functions, >> moving the runtime get into the sysfs code probably involves having >> conditionals for device that support runtime PM at all, otherwise who >> knows what might happen, > > You need special runtime suspend/resume functions so that sysfs access > doesn't try to resurrect the world by accident (and so goes into the > modeset code when not needed). i915 runtime PM does that and a lot > more (we can runtime suspend even when the device is open, debugfs, > sysfs, i2c and any other probing and poking just wake up the minimal > parts of the device and state and so on ...). If you look at our > runtime_suspend/resum functions there's very little we actually do ... Our runtime pm is completely different than i915, since the chip is completely off, with a hard power switch which the GPU isn't aware off so we have to switch it back on again and post it do anything, even probe a connector, and if you post it you may as well reset the mode, granted maybe we don't need to care about the modeset I might play a bit tomorrow with just removing the modeset from the runtime resume path. Dave. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
