[PATCH 2/3] drm/i915: Introduce intel_runtime_pm_disable to pair intel_runtime_pm_enable

[Chris Wilson]

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 at chris-wilson.co.uk>
Cc: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c         | 10 +++++---
 drivers/gpu/drm/i915/intel_drv.h        |  1 +
 drivers/gpu/drm/i915/intel_runtime_pm.c | 33 +++++++++++++++++--------
 3 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 9dce55182c3a..c6585286e82e 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1381,6 +1381,7 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto out_pci_disable;
 
 	intel_runtime_pm_get(dev_priv);
+	intel_runtime_pm_enable(dev_priv);
 
 	ret = i915_driver_init_mmio(dev_priv);
 	if (ret < 0)
@@ -1408,8 +1409,6 @@ 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);
@@ -1423,6 +1422,7 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
 out_cleanup_mmio:
 	i915_driver_cleanup_mmio(dev_priv);
 out_runtime_pm_put:
+	intel_runtime_pm_disable(dev_priv);
 	intel_runtime_pm_put(dev_priv);
 	i915_driver_cleanup_early(dev_priv);
 out_pci_disable:
@@ -1441,13 +1441,13 @@ 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);
@@ -1473,7 +1473,9 @@ void i915_driver_unload(struct drm_device *dev)
 	i915_driver_cleanup_hw(dev_priv);
 	i915_driver_cleanup_mmio(dev_priv);
 
+	intel_runtime_pm_disable(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)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 1295bd8bcd7d..364fc2504fa4 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/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);
 
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index e209edbc561d..398a2060a66a 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -3793,8 +3793,6 @@ 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
@@ -3804,18 +3802,16 @@ void intel_power_domains_fini_hw(struct drm_i915_private *dev_priv)
 	 * 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);
+
+	/* 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");
+	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);
 }
 
 /**
@@ -4073,4 +4069,21 @@ void intel_runtime_pm_enable(struct drm_i915_private *dev_priv)
 	 * intel_power_domains_fini().
 	 */
 	pm_runtime_put_autosuspend(kdev);
+	pm_runtime_allow(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;
+
+	pm_runtime_forbid(kdev);
+	pm_runtime_dont_use_autosuspend(kdev);
+
+	/*
+	 * 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);
 }
-- 
2.18.0