[Bug 74931] [drm:intel_dp_start_link_train] *ERROR* too many voltage retries, give up

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=74931

--- Comment #4 from Imre Deak <imre.deak at gmail.com> ---
Could you give a try to the latest intel-drm-nightly kernel:

git://anongit.freedesktop.org/drm-intel [drm-intel-nightly branch]

If that doesn't work could you try on top of that the patch below? It's just a
wild guess. We force the panel VDD for the time of clock recovery (which fails)
but we don't force it for channel equalization (which succeeds). I don't see
why we would need to force VDD, since turning on the panel should provide the
necessary power. So let's try to do the CR without forcing VDD too.

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index a3cb52f..9524ae6 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1912,9 +1912,9 @@ static void intel_enable_dp(struct intel_encoder
*encoder)

     intel_edp_panel_vdd_on(intel_dp);
     intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
-    intel_dp_start_link_train(intel_dp);
     intel_edp_panel_on(intel_dp);
     edp_panel_vdd_off(intel_dp, true);
+    intel_dp_start_link_train(intel_dp);
     intel_dp_complete_link_train(intel_dp);
     intel_dp_stop_link_train(intel_dp);
 }

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