[Bug 82593] [HSW-M/BYT/BDW/BSW]udevadm unable to monitor HDMI plug/unplug event sporadically

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=82593

--- Comment #6 from Guo Jinxian <jinxianx.guo at intel.com> ---
Created attachment 106892
  --> https://bugs.freedesktop.org/attachment.cgi?id=106892&action=edit
dmesg

(In reply to comment #3)
> (In reply to comment #2)
> > Created attachment 106403 [details]
> > dmesg
> > 
> > (In reply to comment #1)
> > > Please enable drm.debug=0xf to get drm core debugging, *or* apply this patch
> > > to debug the hotplug events:
> > > 
> > > diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> > > index ab1a5f6dde8a..6abf092d9eb4 100644
> > > --- a/drivers/gpu/drm/drm_sysfs.c
> > > +++ b/drivers/gpu/drm/drm_sysfs.c
> > > @@ -481,7 +481,7 @@ void drm_sysfs_hotplug_event(struct drm_device *dev)
> > >  	char *event_string = "HOTPLUG=1";
> > >  	char *envp[] = { event_string, NULL };
> > >  
> > > -	DRM_DEBUG("generating hotplug event\n");
> > > +	DRM_DEBUG_KMS("generating hotplug event\n");
> > >  
> > >  	kobject_uevent_env(&dev->primary->kdev->kobj, KOBJ_CHANGE, envp);
> > >  }
> > > 
> > > Now, doing hotplug and looking at both udevadm monitor and dmesg, do you see
> > > cases where:
> > > 
> > > a) there's the "generating hotplug event" in dmesg, but you do *not* get it
> > > in udevadm monitor
> > > 
> > > *or*
> > > 
> > > b) you do hotplug but the message is not in dmesg and you don't get it in
> > > udevadm either.
> > 
> > Enable drm.debug=0xf, then doing hotplug, the result is case a):the hotplug
> > event is able to catch by dmesg, and not catch by udevadm monitor.
> 
> I can't see "generating hotplug event" in the attached dmesg when you
> hotplug. Whether you end up in that function or not is crucial in figuring
> out where the problem is. Based on the dmesg, I think it's actually b) but I
> can't be sure.
> 
> Based on a hunch, please try reverting
> commit 36cd7444c044806cd2a4e450a8385597221d5d25
> Author: Dave Airlie <airlied at redhat.com>
> Date:   Fri May 2 13:44:18 2014 +1000
> 
>     drm/i915: check connector->encoder before using it.
> 
> and try again.

On latest nightly(7101d84020f63f1da7e0c5d021cdd6be4d515de5) revert commit
above, udevadm monitor still doesn't work.

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