drm/i915: Disable unused power wells left enabled by BIOS

Make sure all unused power wells left enabled by BIOS get disabled
during driver loading and system resume.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5028
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220202104249.2680843-1-imre.deak@intel.com

drivers/gpu/drm/i915/display/intel_display.c

@@ -10664,6 +10664,8 @@ intel_modeset_setup_hw_state(struct drm_device *dev,
 	}
 
 	intel_display_power_put(dev_priv, POWER_DOMAIN_INIT, wakeref);
+
+	intel_power_domains_sanitize_state(dev_priv);
 }
 
 void intel_display_resume(struct drm_device *dev)

drivers/gpu/drm/i915/display/intel_display_power.c

@@ -6213,6 +6213,37 @@ void intel_power_domains_driver_remove(struct drm_i915_private *i915)
 	intel_runtime_pm_put(&i915->runtime_pm, wakeref);
 }
 
+/**
+ * intel_power_domains_sanitize_state - sanitize power domains state
+ * @i915: i915 device instance
+ *
+ * Sanitize the power domains state during driver loading and system resume.
+ * The function will disable all display power wells that BIOS has enabled
+ * without a user for it (any user for a power well has taken a reference
+ * on it by the time this function is called, after the state of all the
+ * pipe, encoder, etc. HW resources have been sanitized).
+ */
+void intel_power_domains_sanitize_state(struct drm_i915_private *i915)
+{
+	struct i915_power_domains *power_domains = &i915->power_domains;
+	struct i915_power_well *power_well;
+
+	mutex_lock(&power_domains->lock);
+
+	for_each_power_well_reverse(i915, power_well) {
+		if (power_well->desc->always_on || power_well->count ||
+		    !power_well->desc->ops->is_enabled(i915, power_well))
+			continue;
+
+		drm_dbg_kms(&i915->drm,
+			    "BIOS left unused %s power well enabled, disabling it\n",
+			    power_well->desc->name);
+		intel_power_well_disable(i915, power_well);
+	}
+
+	mutex_unlock(&power_domains->lock);
+}
+
 /**
  * intel_power_domains_enable - enable toggling of display power wells
  * @i915: i915 device instance

drivers/gpu/drm/i915/display/intel_display_power.h

@@ -218,6 +218,7 @@ void intel_power_domains_disable(struct drm_i915_private *dev_priv);
 void intel_power_domains_suspend(struct drm_i915_private *dev_priv,
 				 enum i915_drm_suspend_mode);
 void intel_power_domains_resume(struct drm_i915_private *dev_priv);
+void intel_power_domains_sanitize_state(struct drm_i915_private *dev_priv);
 
 void intel_display_power_suspend_late(struct drm_i915_private *i915);
 void intel_display_power_resume_early(struct drm_i915_private *i915);