[BUG] i915 HDMI connector status is connected after disconnection

[Chris Chiu]

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

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