[BUG] i915 HDMI connector status is connected after disconnection

[Jani Nikula]

On Wed, 22 Aug 2018, Chris Chiu <chiu at endlessm.com> wrote:
> On Fri, Jul 6, 2018 at 2:44 PM, Chris Chiu <chiu at endlessm.com> wrote:
>> On Thu, Jul 5, 2018 at 10:40 PM, Ville Syrjälä
>> <ville.syrjala at linux.intel.com> wrote:
>>> On Thu, Jul 05, 2018 at 03:58:36PM +0800, Chris Chiu 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
>>>
>>> Pull the cable out faster?
>>>
>>> I presume this is the same old case of hpd disconnecting slightly
>>> before ddc and we still manage to read the EDID when processing
>>> the hpd irq. We kinda tried to fix that with the live status
>>> check but that thing failed spectacularly.
>>>
>>> --
>>> Ville Syrjälä
>>> Intel
>
> There's a patch https://bugs.freedesktop.org/show_bug.cgi?id=107125#c8.
> And I verified on the X705FD/X560UD which were easy to reproduce, the patch
> works as expected. Can anyone kindly give comments about this patch?
> We can do anything to help fix this issue upstream. Thanks

Seems like a hack. Should look into hw based debouncing or a slight
delay in the hotplug work processing I think.

BR,
Jani.

>
> Chris
>
>> Thanks for the suggestion. I tried pulling the cable out faster, the status
>> shows correctly. I also tried branch drm-tip of
>> https://cgit.freedesktop.org/drm/drm-tip
>> but the symptom persists.
>>
>> Anything I can help here? Or any old commit/patch I can try to do some
>> experiments?
>>
>> Chris

-- 
Jani Nikula, Intel Open Source Graphics Center