[Bug 82593] [BYT]udevadm unable to monitor HDMI plug/unplug event sporadically

[bugzilla-daemon at freedesktop.org]

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

Jani Nikula <jani.nikula at intel.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEEDINFO

--- Comment #3 from Jani Nikula <jani.nikula at intel.com> ---
(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.

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