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

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Message-ID: <20180705144009.GC5565@intel.com>
Date:   Thu, 5 Jul 2018 17:40:09 +0300
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Chris Chiu <chiu@...lessm.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 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