[Bug 70839] [IVB] Undocking laptop causes warning in intel_dp_link_down+0x1d2/0x210

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=70839

--- Comment #2 from Yuly Novikov <ynovikov at chromium.org> ---
I encounter a similar stack in ChromeOS when unplugging DP cable.
The reason it happens for me is that intel_dp_link_down() is called first time
from intel_dp_check_link_status() from intel_dp_hot_plug().
Then, during hot plug uevent processing, we decide to DPMS OFF the DP, and then
intel_dp_link_down() is called a second time, so there is a warning for
WARN_ON((I915_READ(intel_dp->output_reg) & DP_PORT_EN) == 0).

I am also getting a warning in intel_modeset_check_state(), since we
reconfigure internal LVDS before we DPMS OFF the DP, and during the check we
hit the warning for DP:
active = encoder->get_hw_state(encoder, &pipe);
WARN(active != encoder->connectors_active,

I'd be happy to upload a fix for that, but I am not sure what would be the
right direction to take with it.
>From reading commit messages for intel_dp_hot_plug(), I understand that it
calls intel_dp_check_link_status() "for userspace apps that don't respond to
hot plug uevents". But that causes the warnings for apps that do respond to
them.

I think that the warnings are irrelevant in this case. I'd like to keep track
of hot plug detection, and then not warn about the DP link being down as a
result of hot unplug.
Daniel, what do you think?

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