[Intel-gfx] [BUG] i915 HDMI connector status is connected after disconnection

[Rodrigo Vivi]

On Fri, Jul 06, 2018 at 10:41:18AM -0700, Guang Bai wrote:
> On Fri, 6 Jul 2018 14:44:58 +0800
> 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  
> > 
> > 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
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> I'm working on a same issue with HP KBL ThinPro laptop where both
> 
> kernel 4.9.79 & 4.15.7 are failing the same way:
> - Unplug the HDMI cable slowly the connector status is still
>   "connected"
> 
> Debugging shows from kernel 4.9 and up to 4.18 drim/i915 behaves the
> same way:
> - When the HDMI calbe is unplugged, there is a transition time when
>   the DDC lines are still connected and i915 can read back the EDID
>   and honors "connected" state
> 
> This problem does not happen on Windows7 & Windows 10 on the same
> failing platform - Windows KMD does *not* read the DDC when seeing the
> corresponding PCH/HPD pins indicating "disconnected" within 300ms-400ms
> period - This checking is done during bottom-half interrupt routines
> 
> I worked patches with both 4.15.7 and 4.17.1 intercepting this Windows
> KMD logics; It seems these patches work for HP KBL ThinPro laptop - My
> patches are being tested by HP team - I was just about to post the open
> discussion on this topic to collect inputs from our community

please send them out anyways ;)

> - Do we have to refactor the HDMI hot-plug handling codes to cope with
>   this long standing issue?

What is your proposal for re-work?

> - Is that OK to add 300ms-500ms delay "msleep(100)" in a loop in the
>   bottom half of interrupt routines?

Well, We fight to add the delays only when they are required by specs,
rather than experimental on single display/configuration...
but/however/nevertheless we have cases that we retry aux communications
32 times because a specific monitor...

please show your patch and we discuss on top of it...

> 
> Regards,
> -Guang
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