[Bug 76987] [BYT Regression]Some subcases of igt/kms_flip timeout

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=76987

--- Comment #2 from Imre Deak <imre.deak at gmail.com> ---
(In reply to comment #1)
> Hm, that warning is fairly old, so no idea why stuff started to go boom here.
> 
> Can you please try to bisect where this regression has been introduced?
> 
> Adding Jani in case it turns out to be the dp aux rework, but the only open
> issue we know of should result in this kind of warning.

dp_aux_ch not started status 0xffffffff

and a bunch of

WARNING: CPU: 0 PID: 4 at drivers/gpu/drm/i915/intel_pm.c:5652
intel_display_power_put+0x39/0xf8 [i915]()

make me think this is a power domain refcounting issue. One idea for the reason
is the unbalanced vdd_on/off calls we discussed and the fix would be (based on
your suggestion):

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index e48d47c..c7a52d1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -313,8 +313,12 @@ static bool edp_have_panel_vdd(struct intel_dp *intel_dp)
 {
     struct drm_device *dev = intel_dp_to_dev(intel_dp);
     struct drm_i915_private *dev_priv = dev->dev_private;
+    struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+    struct intel_encoder *intel_encoder = &intel_dig_port->base;
+    enum intel_display_power_domain power_domain;

-    return !dev_priv->pm.suspended &&
+    power_domain = intel_display_port_power_domain(intel_encoder);
+    return intel_display_power_enabled(dev_priv, power_domain) &&
            (I915_READ(_pp_ctrl_reg(intel_dp)) & EDP_FORCE_VDD) != 0;
 }

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