linux-kernel - Re: [BUG] i915 HDMI connector status is connected after disconnection

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Message-ID: <153078146934.15734.3696654838092752426@skylake-alporthouse-com>
Date:   Thu, 05 Jul 2018 10:04:29 +0100
From:   Chris Wilson <chris@...is-wilson.co.uk>
To:     Chris Chiu <chiu@...lessm.com>, David Airlie <airlied@...ux.ie>,
        Jani Nikula <jani.nikula@...el.com>,
        joonas.lahtinen@...ux.intel.com, rodrigo.vivi@...el.com
Cc:     intel-gfx@...ts.freedesktop.org,
        Linux Upstreaming Team <linux@...lessm.com>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [BUG] i915 HDMI connector status is connected after disconnection

Quoting Jani Nikula (2018-07-05 09:58:57)
> On Thu, 05 Jul 2018, Chris Chiu <chiu@...lessm.com> wrote:
> > Hi,
> >     We have few ASUS laptops X705FD (The new WiskyLake), X560UD (intel
> > i5-8250U), X530UN (intel i7-8550U) share the same problem, which is
> > the HDMI connector status stays connected even the HDMI cable has been
> > unplugged. Look into the "/sys/class/drm/card0-HDMI-A-1/status" for
> > checking the status while plug/unplug the HDMI, it shows
> > "disconnected" before plug in HDMI cable, then switch to "connected"
> > after plugin, and still stay "connected" after unplug. This would
> > cause the audio output path cannot correctly switch from HDMI to
> > internal speaker after unplugging the HDMI.
> >
> > I then try to verify with the latest kernel 4.18.0-rc3+, the bug still
> > present. The full "dmesg" log is here.
> > https://gist.github.com/mschiu77/d761d7c5cf191b7868d4d7788ae087f1
> >
> > The HDMI cable is plugged in at ~26th second.
> > "[ 26.214371] [drm:drm_detect_monitor_audio [drm]] Monitor has basic
> > audio support"
> > then unplug the HDMI at ~73th second.
> > "[ 73.328361] [drm:drm_detect_monitor_audio [drm]] Monitor has basic
> > audio support"
> >
> > Please advise what I can do to fix this. Thanks
> 
> Seems rather odd. Please file a bug report at [1]. Attach the dmesg on
> the bug. Please attach 'xrandr --verbose' output before and after
> unplugging on the bug.

Note that 'xrandr --verbose' will trigger a reprobe of the devices,
papering over any missed probe following hotplug.  I would suggest
preceding with 'xrandr --current --verbose'.

If all you are doing is checking status, you need to 'echo detect >
status' to trigger a reprobe after hotplug.
-Chris