drm/i915: Disable hotplug detection works during driver init/shutdown

As described in the previous patch, an unexpected connector
detection/modeset started from the intel_hotplug::hotplug_work can
happen during the driver init/shutdown sequence. Prevent these by
disabling the queuing of and flushing all the intel_hotplug work that
can start them at the beginning of the init/shutdown sequence and allow
the queuing only while the display is in the initialized state.

Other work items - like the intel_connector::modeset_retry_work or the
MST probe works - are still enabled and can start a detection/modeset,
but after the previous patch these will be rejected. Disabling these
works as well is for a follow-up patchset.

Link: https://patchwork.freedesktop.org/patch/msgid/20240104083008.2715733-9-imre.deak@intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>

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

@@ -174,6 +174,12 @@ struct intel_hotplug {
 	struct work_struct poll_init_work;
 	bool poll_enabled;
 
+	/*
+	 * Queuing of hotplug_work, reenable_work and poll_init_work is
+	 * enabled. Protected by drm_i915_private::irq_lock.
+	 */
+	bool detection_work_enabled;
+
 	unsigned int hpd_storm_threshold;
 	/* Whether or not to count short HPD IRQs in HPD storms */
 	u8 hpd_short_storm_enabled;

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

@@ -309,6 +309,8 @@ static void set_display_access(struct drm_i915_private *i915,
 void intel_display_driver_enable_user_access(struct drm_i915_private *i915)
 {
 	set_display_access(i915, true, NULL);
+
+	intel_hpd_enable_detection_work(i915);
 }
 
 /**
@@ -330,6 +332,8 @@ void intel_display_driver_enable_user_access(struct drm_i915_private *i915)
  */
 void intel_display_driver_disable_user_access(struct drm_i915_private *i915)
 {
+	intel_hpd_disable_detection_work(i915);
+
 	set_display_access(i915, false, current);
 }
 

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

@@ -6019,7 +6019,7 @@ static void intel_dp_oob_hotplug_event(struct drm_connector *connector)
 	spin_lock_irq(&i915->irq_lock);
 	i915->display.hotplug.event_bits |= BIT(encoder->hpd_pin);
 	spin_unlock_irq(&i915->irq_lock);
-	queue_delayed_work(i915->unordered_wq, &i915->display.hotplug.hotplug_work, 0);
+	intel_hpd_schedule_detection(i915);
 }
 
 static const struct drm_connector_funcs intel_dp_connector_funcs = {

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

@@ -177,6 +177,46 @@ static bool intel_hpd_irq_storm_detect(struct drm_i915_private *dev_priv,
 	return storm;
 }
 
+static bool detection_work_enabled(struct drm_i915_private *i915)
+{
+	lockdep_assert_held(&i915->irq_lock);
+
+	return i915->display.hotplug.detection_work_enabled;
+}
+
+static bool
+mod_delayed_detection_work(struct drm_i915_private *i915, struct delayed_work *work, int delay)
+{
+	lockdep_assert_held(&i915->irq_lock);
+
+	if (!detection_work_enabled(i915))
+		return false;
+
+	return mod_delayed_work(i915->unordered_wq, work, delay);
+}
+
+static bool
+queue_delayed_detection_work(struct drm_i915_private *i915, struct delayed_work *work, int delay)
+{
+	lockdep_assert_held(&i915->irq_lock);
+
+	if (!detection_work_enabled(i915))
+		return false;
+
+	return queue_delayed_work(i915->unordered_wq, work, delay);
+}
+
+static bool
+queue_detection_work(struct drm_i915_private *i915, struct work_struct *work)
+{
+	lockdep_assert_held(&i915->irq_lock);
+
+	if (!detection_work_enabled(i915))
+		return false;
+
+	return queue_work(i915->unordered_wq, work);
+}
+
 static void
 intel_hpd_irq_storm_switch_to_polling(struct drm_i915_private *dev_priv)
 {
@@ -213,9 +253,9 @@ intel_hpd_irq_storm_switch_to_polling(struct drm_i915_private *dev_priv)
 	/* Enable polling and queue hotplug re-enabling. */
 	if (hpd_disabled) {
 		drm_kms_helper_poll_reschedule(&dev_priv->drm);
-		mod_delayed_work(dev_priv->unordered_wq,
-				 &dev_priv->display.hotplug.reenable_work,
-				 msecs_to_jiffies(HPD_STORM_REENABLE_DELAY));
+		mod_delayed_detection_work(dev_priv,
+					   &dev_priv->display.hotplug.reenable_work,
+					   msecs_to_jiffies(HPD_STORM_REENABLE_DELAY));
 	}
 }
 
@@ -348,9 +388,9 @@ static void i915_digport_work_func(struct work_struct *work)
 	if (old_bits) {
 		spin_lock_irq(&dev_priv->irq_lock);
 		dev_priv->display.hotplug.event_bits |= old_bits;
+		queue_delayed_detection_work(dev_priv,
+					     &dev_priv->display.hotplug.hotplug_work, 0);
 		spin_unlock_irq(&dev_priv->irq_lock);
-		queue_delayed_work(dev_priv->unordered_wq,
-				   &dev_priv->display.hotplug.hotplug_work, 0);
 	}
 }
 
@@ -467,11 +507,11 @@ static void i915_hotplug_work_func(struct work_struct *work)
 	if (retry) {
 		spin_lock_irq(&dev_priv->irq_lock);
 		dev_priv->display.hotplug.retry_bits |= retry;
-		spin_unlock_irq(&dev_priv->irq_lock);
 
-		mod_delayed_work(dev_priv->unordered_wq,
-				 &dev_priv->display.hotplug.hotplug_work,
-				 msecs_to_jiffies(HPD_RETRY_DELAY));
+		mod_delayed_detection_work(dev_priv,
+					   &dev_priv->display.hotplug.hotplug_work,
+					   msecs_to_jiffies(HPD_RETRY_DELAY));
+		spin_unlock_irq(&dev_priv->irq_lock);
 	}
 }
 
@@ -590,7 +630,6 @@ void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
 	 */
 	if (storm_detected)
 		intel_hpd_irq_setup(dev_priv);
-	spin_unlock(&dev_priv->irq_lock);
 
 	/*
 	 * Our hotplug handler can grab modeset locks (by calling down into the
@@ -601,8 +640,10 @@ void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
 	if (queue_dig)
 		queue_work(dev_priv->display.hotplug.dp_wq, &dev_priv->display.hotplug.dig_port_work);
 	if (queue_hp)
-		queue_delayed_work(dev_priv->unordered_wq,
-				   &dev_priv->display.hotplug.hotplug_work, 0);
+		queue_delayed_detection_work(dev_priv,
+					     &dev_priv->display.hotplug.hotplug_work, 0);
+
+	spin_unlock(&dev_priv->irq_lock);
 }
 
 /**
@@ -781,8 +822,10 @@ void intel_hpd_poll_enable(struct drm_i915_private *dev_priv)
 	 * As well, there's no issue if we race here since we always reschedule
 	 * this worker anyway
 	 */
-	queue_work(dev_priv->unordered_wq,
-		   &dev_priv->display.hotplug.poll_init_work);
+	spin_lock_irq(&dev_priv->irq_lock);
+	queue_detection_work(dev_priv,
+			     &dev_priv->display.hotplug.poll_init_work);
+	spin_unlock_irq(&dev_priv->irq_lock);
 }
 
 /**
@@ -810,8 +853,11 @@ void intel_hpd_poll_disable(struct drm_i915_private *dev_priv)
 		return;
 
 	WRITE_ONCE(dev_priv->display.hotplug.poll_enabled, false);
-	queue_work(dev_priv->unordered_wq,
-		   &dev_priv->display.hotplug.poll_init_work);
+
+	spin_lock_irq(&dev_priv->irq_lock);
+	queue_detection_work(dev_priv,
+			     &dev_priv->display.hotplug.poll_init_work);
+	spin_unlock_irq(&dev_priv->irq_lock);
 }
 
 void intel_hpd_init_early(struct drm_i915_private *i915)
@@ -833,6 +879,20 @@ void intel_hpd_init_early(struct drm_i915_private *i915)
 	i915->display.hotplug.hpd_short_storm_enabled = !HAS_DP_MST(i915);
 }
 
+static bool cancel_all_detection_work(struct drm_i915_private *i915)
+{
+	bool was_pending = false;
+
+	if (cancel_delayed_work_sync(&i915->display.hotplug.hotplug_work))
+		was_pending = true;
+	if (cancel_work_sync(&i915->display.hotplug.poll_init_work))
+		was_pending = true;
+	if (cancel_delayed_work_sync(&i915->display.hotplug.reenable_work))
+		was_pending = true;
+
+	return was_pending;
+}
+
 void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 {
 	if (!HAS_DISPLAY(dev_priv))
@@ -848,9 +908,13 @@ void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 	spin_unlock_irq(&dev_priv->irq_lock);
 
 	cancel_work_sync(&dev_priv->display.hotplug.dig_port_work);
-	cancel_delayed_work_sync(&dev_priv->display.hotplug.hotplug_work);
-	cancel_work_sync(&dev_priv->display.hotplug.poll_init_work);
-	cancel_delayed_work_sync(&dev_priv->display.hotplug.reenable_work);
+
+	/*
+	 * All other work triggered by hotplug events should be canceled by
+	 * now.
+	 */
+	if (cancel_all_detection_work(dev_priv))
+		drm_dbg_kms(&dev_priv->drm, "Hotplug detection work still active\n");
 }
 
 bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
@@ -880,6 +944,62 @@ void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
 	spin_unlock_irq(&dev_priv->irq_lock);
 }
 
+static void queue_work_for_missed_irqs(struct drm_i915_private *i915)
+{
+	bool queue_work = false;
+	enum hpd_pin pin;
+
+	lockdep_assert_held(&i915->irq_lock);
+
+	if (i915->display.hotplug.event_bits ||
+	    i915->display.hotplug.retry_bits)
+		queue_work = true;
+
+	for_each_hpd_pin(pin) {
+		switch (i915->display.hotplug.stats[pin].state) {
+		case HPD_MARK_DISABLED:
+			queue_work = true;
+			break;
+		case HPD_ENABLED:
+			break;
+		default:
+			MISSING_CASE(i915->display.hotplug.stats[pin].state);
+		}
+	}
+
+	if (queue_work)
+		queue_delayed_detection_work(i915, &i915->display.hotplug.hotplug_work, 0);
+}
+
+void intel_hpd_enable_detection_work(struct drm_i915_private *i915)
+{
+	spin_lock_irq(&i915->irq_lock);
+	i915->display.hotplug.detection_work_enabled = true;
+	queue_work_for_missed_irqs(i915);
+	spin_unlock_irq(&i915->irq_lock);
+}
+
+void intel_hpd_disable_detection_work(struct drm_i915_private *i915)
+{
+	spin_lock_irq(&i915->irq_lock);
+	i915->display.hotplug.detection_work_enabled = false;
+	spin_unlock_irq(&i915->irq_lock);
+
+	cancel_all_detection_work(i915);
+}
+
+bool intel_hpd_schedule_detection(struct drm_i915_private *i915)
+{
+	unsigned long flags;
+	bool ret;
+
+	spin_lock_irqsave(&i915->irq_lock, flags);
+	ret = queue_delayed_detection_work(i915, &i915->display.hotplug.hotplug_work, 0);
+	spin_unlock_irqrestore(&i915->irq_lock, flags);
+
+	return ret;
+}
+
 static int i915_hpd_storm_ctl_show(struct seq_file *m, void *data)
 {
 	struct drm_i915_private *dev_priv = m->private;

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

@@ -30,4 +30,8 @@ bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
 void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
 void intel_hpd_debugfs_register(struct drm_i915_private *i915);
 
+void intel_hpd_enable_detection_work(struct drm_i915_private *i915);
+void intel_hpd_disable_detection_work(struct drm_i915_private *i915);
+bool intel_hpd_schedule_detection(struct drm_i915_private *i915);
+
 #endif /* __INTEL_HOTPLUG_H__ */