drm/i915: Introduce intel_runtime_pm_disable to pair intel_runtime_pm_enable

Currently, we cancel the extra wakeref we have for !runtime-pm devices
inside power_wells_fini_hw. However, this is not strictly paired with
the acquisition of that wakeref in runtime_pm_enable (as the fini_hw may
be called on errors paths before we even call runtime_pm_enable). Make
the symmetry more explicit and include a check that we do release all of
our rpm wakerefs.

v2: Fixup transfer of ownership back to core whilst keeping our wakeref
count balanced.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180816123757.3286-1-imre.deak@intel.com

drivers/gpu/drm/i915/i915_drv.c

@@ -1281,6 +1281,8 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
 	 */
 	if (INTEL_INFO(dev_priv)->num_pipes)
 		drm_kms_helper_poll_init(dev);
+
+	intel_runtime_pm_enable(dev_priv);
 }
 
 /**
@@ -1289,6 +1291,8 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
  */
 static void i915_driver_unregister(struct drm_i915_private *dev_priv)
 {
+	intel_runtime_pm_disable(dev_priv);
+
 	intel_fbdev_unregister(dev_priv);
 	intel_audio_deinit(dev_priv);
 
@@ -1366,16 +1370,6 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto out_fini;
 
 	pci_set_drvdata(pdev, &dev_priv->drm);
-	/*
-	 * Disable the system suspend direct complete optimization, which can
-	 * leave the device suspended skipping the driver's suspend handlers
-	 * if the device was already runtime suspended. This is needed due to
-	 * the difference in our runtime and system suspend sequence and
-	 * becaue the HDA driver may require us to enable the audio power
-	 * domain during system suspend.
-	 */
-	dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_NEVER_SKIP);
-
 	ret = i915_driver_init_early(dev_priv, ent);
 	if (ret < 0)
 		goto out_pci_disable;
@@ -1408,8 +1402,6 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	i915_driver_register(dev_priv);
 
-	intel_runtime_pm_enable(dev_priv);
-
 	intel_init_ipc(dev_priv);
 
 	intel_runtime_pm_put(dev_priv);
@@ -1441,13 +1433,13 @@ void i915_driver_unload(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct pci_dev *pdev = dev_priv->drm.pdev;
 
+	intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
+
 	i915_driver_unregister(dev_priv);
 
 	if (i915_gem_suspend(dev_priv))
 		DRM_ERROR("failed to idle hardware; continuing to unload!\n");
 
-	intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
-
 	drm_atomic_helper_shutdown(dev);
 
 	intel_gvt_cleanup(dev_priv);
@@ -1474,6 +1466,7 @@ void i915_driver_unload(struct drm_device *dev)
 	i915_driver_cleanup_mmio(dev_priv);
 
 	intel_display_power_put(dev_priv, POWER_DOMAIN_INIT);
+	WARN_ON(atomic_read(&dev_priv->runtime_pm.wakeref_count));
 }
 
 static void i915_driver_release(struct drm_device *dev)

drivers/gpu/drm/i915/intel_drv.h

@@ -1959,6 +1959,7 @@ void intel_power_domains_verify_state(struct drm_i915_private *dev_priv);
 void bxt_display_core_init(struct drm_i915_private *dev_priv, bool resume);
 void bxt_display_core_uninit(struct drm_i915_private *dev_priv);
 void intel_runtime_pm_enable(struct drm_i915_private *dev_priv);
+void intel_runtime_pm_disable(struct drm_i915_private *dev_priv);
 const char *
 intel_display_power_domain_str(enum intel_display_power_domain domain);
 

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -3793,29 +3793,19 @@ void intel_power_domains_init_hw(struct drm_i915_private *dev_priv, bool resume)
  */
 void intel_power_domains_fini_hw(struct drm_i915_private *dev_priv)
 {
-	struct device *kdev = &dev_priv->drm.pdev->dev;
-
 	/*
 	 * The i915.ko module is still not prepared to be loaded when
 	 * the power well is not enabled, so just enable it in case
 	 * we're going to unload/reload.
-	 * The following also reacquires the RPM reference the core passed
-	 * to the driver during loading, which is dropped in
-	 * intel_runtime_pm_enable(). We have to hand back the control of the
-	 * device to the core with this reference held.
 	 */
-	intel_display_set_init_power(dev_priv, true);
+	intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
+
+	/* Keep the power well enabled, but cancel its rpm wakeref. */
+	intel_runtime_pm_put(dev_priv);
 
 	/* Remove the refcount we took to keep power well support disabled. */
 	if (!i915_modparams.disable_power_well)
 		intel_display_power_put(dev_priv, POWER_DOMAIN_INIT);
-
-	/*
-	 * Remove the refcount we took in intel_runtime_pm_enable() in case
-	 * the platform doesn't support runtime PM.
-	 */
-	if (!HAS_RUNTIME_PM(dev_priv))
-		pm_runtime_put(kdev);
 }
 
 /**
@@ -4048,6 +4038,16 @@ void intel_runtime_pm_enable(struct drm_i915_private *dev_priv)
 	struct pci_dev *pdev = dev_priv->drm.pdev;
 	struct device *kdev = &pdev->dev;
 
+	/*
+	 * Disable the system suspend direct complete optimization, which can
+	 * leave the device suspended skipping the driver's suspend handlers
+	 * if the device was already runtime suspended. This is needed due to
+	 * the difference in our runtime and system suspend sequence and
+	 * becaue the HDA driver may require us to enable the audio power
+	 * domain during system suspend.
+	 */
+	dev_pm_set_driver_flags(kdev, DPM_FLAG_NEVER_SKIP);
+
 	pm_runtime_set_autosuspend_delay(kdev, 10000); /* 10s */
 	pm_runtime_mark_last_busy(kdev);
 
@@ -4074,3 +4074,18 @@ void intel_runtime_pm_enable(struct drm_i915_private *dev_priv)
 	 */
 	pm_runtime_put_autosuspend(kdev);
 }
+
+void intel_runtime_pm_disable(struct drm_i915_private *dev_priv)
+{
+	struct pci_dev *pdev = dev_priv->drm.pdev;
+	struct device *kdev = &pdev->dev;
+
+	/* Transfer rpm ownership back to core */
+	WARN(pm_runtime_get_sync(&dev_priv->drm.pdev->dev) < 0,
+	     "Failed to pass rpm ownership back to core\n");
+
+	pm_runtime_dont_use_autosuspend(kdev);
+
+	if (!HAS_RUNTIME_PM(dev_priv))
+		pm_runtime_put(kdev);
+}