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

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Date:   Fri, 6 Jul 2018 14:44:58 +0800
From:   Chris Chiu <chiu@...lessm.com>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     Jani Nikula <jani.nikula@...el.com>,
        joonas.lahtinen@...ux.intel.com, rodrigo.vivi@...el.com,
        David Airlie <airlied@...ux.ie>,
        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

On Thu, Jul 5, 2018 at 10:40 PM, Ville Syrjälä
<ville.syrjala@...ux.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

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