[Intel-gfx] [PATCH] drm/i915: Fix the HDMI hot plug disconnection failure (v2)

[Guang Bai]

On Tue, 13 Nov 2018 13:07:46 +0200
Jani Nikula <jani.nikula at intel.com> wrote:

> On Mon, 12 Nov 2018, Guang Bai <guang.bai at intel.com> wrote:
> > Actually I'm still working on it right now with
> > DRM_MODE_CONNECTOR_HDMIA/HDMIB, recommended by James, I'm able to
> > differentiate the HDMI or DP even the encoder type is the
> > "INTEL_OUTPUT_DDI", I still have the "trybot" intermittent test
> > failures with new DRM connector types. Even worse, there is phantom
> > "intel_encoder_hotplug()" call following the correct one:
> > When connecting both DP and HDMI on the platform, unplug the DP, the
> > "i915_hotplug_work_func()" first calls the "intel_encoder_hotplug()"
> > with DP encoder, then calls again with HDMI encoder.
> > I haven't identified if the work function get queued twice or itself
> > is incorrectly identifying wrong encoder hotplut status. Will try to
> > get everything cleaned up ASAP.  
> 
> Frankly I liked the simplicity of [1] over the patch in this thread.
> It fixed the real-world use case Chris Chiu has, but I understand
> that it still failed the slow unplug HDMI test case you have. The
> problem is, we have zero visibility to the test case you have. Is it
> automated or manual? Can we see the specs or source code for the test
> case?
> 
> If we have to consider the live status unreliable, it's possible to
> devise a pathological test case that will always fail, regardless of
> what we do in the driver. Does the test case reflect real world usage?
> 
> Also Cc: Ville for input.
> 
> BR,
> Jani.
> 
Hi Jani, Ville & Chris (Chiu):
Sorry for the late reply as I have beening bumping around different
projects and also spent sometime to investigate [v2] failures with
testing the codes on trybot
1. My testcase: I have one+ customer KBL laptop and uBuntu16.04
running, slowly unplug the HDMI cable (wiggling), the issue can be
reproduced very easily - Just check kernel HDMI-A-1 connecting states
2. I belive Chris is using roughly the same test case?
3. I don't like the [v2] solution either since it's *not* clean and
have intermittent trybot/patchwork failures
4. with latest drm-tip codes, I'm able to workout a very clean solution
[v3] today and it passes the patchwork tests - Would you like to try it
out and also review the change?
Thanks,
Guang
> 
> 
> [1]
> http://patchwork.freedesktop.org/patch/msgid/20180925071836.24711-1-jani.nikula@intel.com
> 
>