[Bug 76151] [HSW-M GT3e bisected]Blackscreen after booting with HDMI only

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=76151

--- Comment #5 from Chris Wilson <chris at chris-wilson.co.uk> ---
Ugh, that interleaves the lifetime of the pm vs forcewake ref.

reg read: -> deferred forcewake.
gen6_gt_get: -> pm_get, forcewake++
gen6_gt_put: -> --forcewake, pm_put

device is now asleep

forcewake_timer: boom, invalid reg access.


diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index b8b59752562a..e92bdcef5342 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5877,6 +5877,8 @@ void intel_runtime_pm_put(struct drm_i915_private
*dev_priv)
     if (!HAS_RUNTIME_PM(dev))
         return;

+    del_timer_sync(&dev_priv->uncore.force_wake_timer);
+
     pm_runtime_mark_last_busy(device);
     pm_runtime_put_autosuspend(device);
 }
diff --git a/drivers/gpu/drm/i915/intel_uncore.c
b/drivers/gpu/drm/i915/intel_uncore.c
index e6bb421a3dbd..527527382361 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -304,8 +304,6 @@ static void gen6_force_wake_timer(unsigned long arg)
     if (--dev_priv->uncore.forcewake_count == 0)
         dev_priv->uncore.funcs.force_wake_put(dev_priv, FORCEWAKE_ALL);
     spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
-
-    intel_runtime_pm_put(dev_priv);
 }

 static void intel_uncore_forcewake_reset(struct drm_device *dev, bool restore)
@@ -439,7 +437,6 @@ void gen6_gt_force_wake_get(struct drm_i915_private
*dev_priv, int fw_engine)
 void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv, int fw_engine)
 {
     unsigned long irqflags;
-    bool delayed = false;

     if (!dev_priv->uncore.funcs.force_wake_put)
         return;
@@ -450,19 +447,17 @@ void gen6_gt_force_wake_put(struct drm_i915_private
*dev_priv, int fw_engine)
         goto out;
     }

-
     spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
     if (--dev_priv->uncore.forcewake_count == 0) {
         dev_priv->uncore.forcewake_count++;
-        delayed = true;
         mod_timer_pinned(&dev_priv->uncore.force_wake_timer,
                  jiffies + 1);
     }
+
     spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);

 out:
-    if (!delayed)
-        intel_runtime_pm_put(dev_priv);
+    intel_runtime_pm_put(dev_priv);
 }

 void assert_force_wake_inactive(struct drm_i915_private *dev_priv)

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