drm/i915: Add way to specify the power-off delay of a display power domain

Add support for specifying a delay different than the current 100 ms
default for powering off a display power domain. This is needed by the
next patch which delays re-enabling DC states during modesets to avoid
the off->on->off toggling overhead of the DC_off power well, but does
this using a < 100 ms delay for a better utilization of DC power saving
states.
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230616185104.2502003-3-imre.deak@intel.com

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

@@ -458,6 +458,17 @@ async_put_domains_clear_domain(struct i915_power_domains *power_domains,
 	clear_bit(domain, power_domains->async_put_domains[1].bits);
 }
 
+static void
+cancel_async_put_work(struct i915_power_domains *power_domains, bool sync)
+{
+	if (sync)
+		cancel_delayed_work_sync(&power_domains->async_put_work);
+	else
+		cancel_delayed_work(&power_domains->async_put_work);
+
+	power_domains->async_put_next_delay = 0;
+}
+
 static bool
 intel_display_power_grab_async_put_ref(struct drm_i915_private *dev_priv,
 				       enum intel_display_power_domain domain)
@@ -478,7 +489,7 @@ intel_display_power_grab_async_put_ref(struct drm_i915_private *dev_priv,
 	if (!bitmap_empty(async_put_mask.bits, POWER_DOMAIN_NUM))
 		goto out_verify;
 
-	cancel_delayed_work(&power_domains->async_put_work);
+	cancel_async_put_work(power_domains, false);
 	intel_runtime_pm_put_raw(&dev_priv->runtime_pm,
 				 fetch_and_zero(&power_domains->async_put_wakeref));
 out_verify:
@@ -609,7 +620,8 @@ static void __intel_display_power_put(struct drm_i915_private *dev_priv,
 
 static void
 queue_async_put_domains_work(struct i915_power_domains *power_domains,
-			     intel_wakeref_t wakeref)
+			     intel_wakeref_t wakeref,
+			     int delay_ms)
 {
 	struct drm_i915_private *i915 = container_of(power_domains,
 						     struct drm_i915_private,
@@ -618,7 +630,7 @@ queue_async_put_domains_work(struct i915_power_domains *power_domains,
 	power_domains->async_put_wakeref = wakeref;
 	drm_WARN_ON(&i915->drm, !queue_delayed_work(system_unbound_wq,
 						    &power_domains->async_put_work,
-						    msecs_to_jiffies(100)));
+						    msecs_to_jiffies(delay_ms)));
 }
 
 static void
@@ -681,13 +693,15 @@ intel_display_power_put_async_work(struct work_struct *work)
 		bitmap_zero(power_domains->async_put_domains[1].bits,
 			    POWER_DOMAIN_NUM);
 		queue_async_put_domains_work(power_domains,
-					     fetch_and_zero(&new_work_wakeref));
+					     fetch_and_zero(&new_work_wakeref),
+					     power_domains->async_put_next_delay);
+		power_domains->async_put_next_delay = 0;
 	} else {
 		/*
 		 * Cancel the work that got queued after this one got dequeued,
 		 * since here we released the corresponding async-put reference.
 		 */
-		cancel_delayed_work(&power_domains->async_put_work);
+		cancel_async_put_work(power_domains, false);
 	}
 
 out_verify:
@@ -706,19 +720,25 @@ intel_display_power_put_async_work(struct work_struct *work)
  * @i915: i915 device instance
  * @domain: power domain to reference
  * @wakeref: wakeref acquired for the reference that is being released
+ * @delay_ms: delay of powering down the power domain
  *
  * This function drops the power domain reference obtained by
  * intel_display_power_get*() and schedules a work to power down the
  * corresponding hardware block if this is the last reference.
+ * The power down is delayed by @delay_ms if this is >= 0, or by a default
+ * 100 ms otherwise.
  */
 void __intel_display_power_put_async(struct drm_i915_private *i915,
 				     enum intel_display_power_domain domain,
-				     intel_wakeref_t wakeref)
+				     intel_wakeref_t wakeref,
+				     int delay_ms)
 {
 	struct i915_power_domains *power_domains = &i915->display.power.domains;
 	struct intel_runtime_pm *rpm = &i915->runtime_pm;
 	intel_wakeref_t work_wakeref = intel_runtime_pm_get_raw(rpm);
 
+	delay_ms = delay_ms >= 0 ? delay_ms : 100;
+
 	mutex_lock(&power_domains->lock);
 
 	if (power_domains->domain_use_count[domain] > 1) {
@@ -732,10 +752,13 @@ void __intel_display_power_put_async(struct drm_i915_private *i915,
 	/* Let a pending work requeue itself or queue a new one. */
 	if (power_domains->async_put_wakeref) {
 		set_bit(domain, power_domains->async_put_domains[1].bits);
+		power_domains->async_put_next_delay = max(power_domains->async_put_next_delay,
+							  delay_ms);
 	} else {
 		set_bit(domain, power_domains->async_put_domains[0].bits);
 		queue_async_put_domains_work(power_domains,
-					     fetch_and_zero(&work_wakeref));
+					     fetch_and_zero(&work_wakeref),
+					     delay_ms);
 	}
 
 out_verify:
@@ -775,7 +798,7 @@ void intel_display_power_flush_work(struct drm_i915_private *i915)
 
 	async_put_domains_mask(power_domains, &async_put_mask);
 	release_async_put_domains(power_domains, &async_put_mask);
-	cancel_delayed_work(&power_domains->async_put_work);
+	cancel_async_put_work(power_domains, false);
 
 out_verify:
 	verify_async_put_domains_state(power_domains);
@@ -799,7 +822,7 @@ intel_display_power_flush_work_sync(struct drm_i915_private *i915)
 	struct i915_power_domains *power_domains = &i915->display.power.domains;
 
 	intel_display_power_flush_work(i915);
-	cancel_delayed_work_sync(&power_domains->async_put_work);
+	cancel_async_put_work(power_domains, true);
 
 	verify_async_put_domains_state(power_domains);
 

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

@@ -151,6 +151,7 @@ struct i915_power_domains {
 	struct delayed_work async_put_work;
 	intel_wakeref_t async_put_wakeref;
 	struct intel_power_domain_mask async_put_domains[2];
+	int async_put_next_delay;
 
 	struct i915_power_well *power_wells;
 };
@@ -197,7 +198,8 @@ intel_display_power_get_if_enabled(struct drm_i915_private *dev_priv,
 				   enum intel_display_power_domain domain);
 void __intel_display_power_put_async(struct drm_i915_private *i915,
 				     enum intel_display_power_domain domain,
-				     intel_wakeref_t wakeref);
+				     intel_wakeref_t wakeref,
+				     int delay_ms);
 void intel_display_power_flush_work(struct drm_i915_private *i915);
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
 void intel_display_power_put(struct drm_i915_private *dev_priv,
@@ -208,7 +210,16 @@ intel_display_power_put_async(struct drm_i915_private *i915,
 			      enum intel_display_power_domain domain,
 			      intel_wakeref_t wakeref)
 {
-	__intel_display_power_put_async(i915, domain, wakeref);
+	__intel_display_power_put_async(i915, domain, wakeref, -1);
+}
+
+static inline void
+intel_display_power_put_async_delay(struct drm_i915_private *i915,
+				    enum intel_display_power_domain domain,
+				    intel_wakeref_t wakeref,
+				    int delay_ms)
+{
+	__intel_display_power_put_async(i915, domain, wakeref, delay_ms);
 }
 #else
 void intel_display_power_put_unchecked(struct drm_i915_private *dev_priv,
@@ -227,7 +238,16 @@ intel_display_power_put_async(struct drm_i915_private *i915,
 			      enum intel_display_power_domain domain,
 			      intel_wakeref_t wakeref)
 {
-	__intel_display_power_put_async(i915, domain, -1);
+	__intel_display_power_put_async(i915, domain, -1, -1);
+}
+
+static inline void
+intel_display_power_put_async_delay(struct drm_i915_private *i915,
+				    enum intel_display_power_domain domain,
+				    intel_wakeref_t wakeref,
+				    int delay_ms)
+{
+	__intel_display_power_put_async(i915, domain, -1, delay_ms);
 }
 #endif