[Intel-gfx] [PATCH 3/6] drm/i915/display: Implement intel_display_power_wait_enable_ack()

[José Roberto de Souza]

This function is meant to be used after
intel_display_power_get_without_ack() this way we can be sure that the
HW tied to the powerdomain will be powered and ready.

Cc: Imre Deak <imre.deak at intel.com>
Cc: Cooper Chiou <cooper.chiou at intel.com>
Cc: Kai-Heng Feng <kai.heng.feng at canonical.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 .../drm/i915/display/intel_display_power.c    | 29 +++++++++++++++++++
 .../drm/i915/display/intel_display_power.h    |  9 ++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index 9035b220dfa0..a7e531b64e16 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -2328,6 +2328,35 @@ intel_display_power_flush_work_sync(struct drm_i915_private *i915)
 	drm_WARN_ON(&i915->drm, power_domains->async_put_wakeref);
 }
 
+/**
+ * intel_display_power_wait_enable_ack - wait for enabled hardware ack
+ * @dev_priv: i915 device instance
+ * @domain: power domain to reference
+ *
+ * This function must be called after intel_display_power_get_without_ack() and
+ * only in power domains that implements it.
+ */
+void intel_display_power_wait_enable_ack(struct drm_i915_private *dev_priv,
+					 enum intel_display_power_domain domain)
+{
+	struct i915_power_domains *power_domains = &dev_priv->power_domains;
+	struct i915_power_well *power_well;
+
+	mutex_lock(&power_domains->lock);
+
+	for_each_power_domain_well_reverse(dev_priv, power_well,
+					   BIT_ULL(domain)) {
+		if (drm_WARN_ON(&dev_priv->drm,
+				!power_well->desc->ops->wait_enable_ack))
+			break;
+
+		power_well->desc->ops->wait_enable_ack(dev_priv, power_well);
+		break;
+	}
+
+	mutex_unlock(&power_domains->lock);
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
 /**
  * intel_display_power_put - release a power domain reference
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
index 5db86cc862c3..108096177deb 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.h
+++ b/drivers/gpu/drm/i915/display/intel_display_power.h
@@ -148,6 +148,13 @@ struct i915_power_well_ops {
 	/* Returns the hw enabled state. */
 	bool (*is_enabled)(struct drm_i915_private *dev_priv,
 			   struct i915_power_well *power_well);
+
+	/*
+	 * Waits for hardware enabling ack, this is meant to be used together
+	 * with enable_without_ack() and also optional.
+	 */
+	void (*wait_enable_ack)(struct drm_i915_private *dev_priv,
+				struct i915_power_well *power_well);
 };
 
 struct i915_power_well_regs {
@@ -291,6 +298,8 @@ void __intel_display_power_put_async(struct drm_i915_private *i915,
 				     enum intel_display_power_domain domain,
 				     intel_wakeref_t wakeref);
 void intel_display_power_flush_work(struct drm_i915_private *i915);
+void intel_display_power_wait_enable_ack(struct drm_i915_private *dev_priv,
+					 enum intel_display_power_domain domain);
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
 void intel_display_power_put(struct drm_i915_private *dev_priv,
 			     enum intel_display_power_domain domain,
-- 
2.25.2