drm/i915: Add Reenable Timer to turn Hotplug Detection back on (v4)

We disable hoptplug detection when we encounter a hotplug event
storm. Still hotplug detection is required on some outputs (like
Display Port). The interrupt storm may be only temporary (on certain
Dell Laptops for instance it happens at certain charging states of
the system). Thus we enable it after a certain grace period (2 minutes).
Should the interrupt storm persist it will be detected immediately
and it will be disabled again.

v2: Reordered drm_i915_private: moved hotplug_reenable_timer to hpd state tracker.
v3: Clarified loop start value,
    Removed superfluous test for Ivybridge and Haswell,
    Restructured loop to avoid deep nesting (all suggested by Ville Syrjälä)
v4: Fixed two bugs pointed out by Jani Nikula.

Signed-off-by: Egbert Eich <eich@suse.de>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -941,6 +941,7 @@ typedef struct drm_i915_private {
 			HPD_MARK_DISABLED = 2
 		} hpd_mark;
 	} hpd_stats[HPD_NUM_PINS];
+	struct timer_list hotplug_reenable_timer;
 
 	int num_pch_pll;
 	int num_plane;

drivers/gpu/drm/i915/i915_irq.c

@@ -337,6 +337,8 @@ static int i915_get_vblank_timestamp(struct drm_device *dev, int pipe,
 /*
  * Handle hotplug events outside the interrupt handler proper.
  */
+#define I915_REENABLE_HOTPLUG_DELAY (2*60*1000)
+
 static void i915_hotplug_work_func(struct work_struct *work)
 {
 	drm_i915_private_t *dev_priv = container_of(work, drm_i915_private_t,
@@ -375,8 +377,11 @@ static void i915_hotplug_work_func(struct work_struct *work)
 	 /* if there were no outputs to poll, poll was disabled,
 	  * therefore make sure it's enabled when disabling HPD on
 	  * some connectors */
-	if (hpd_disabled)
+	if (hpd_disabled) {
 		drm_kms_helper_poll_enable(dev);
+		mod_timer(&dev_priv->hotplug_reenable_timer,
+			  jiffies + msecs_to_jiffies(I915_REENABLE_HOTPLUG_DELAY));
+	}
 
 	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 
@@ -2367,6 +2372,8 @@ static void valleyview_irq_uninstall(struct drm_device *dev)
 	if (!dev_priv)
 		return;
 
+	del_timer_sync(&dev_priv->hotplug_reenable_timer);
+
 	for_each_pipe(pipe)
 		I915_WRITE(PIPESTAT(pipe), 0xffff);
 
@@ -2388,6 +2395,8 @@ static void ironlake_irq_uninstall(struct drm_device *dev)
 	if (!dev_priv)
 		return;
 
+	del_timer_sync(&dev_priv->hotplug_reenable_timer);
+
 	I915_WRITE(HWSTAM, 0xffffffff);
 
 	I915_WRITE(DEIMR, 0xffffffff);
@@ -2767,6 +2776,8 @@ static void i915_irq_uninstall(struct drm_device * dev)
 	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
 	int pipe;
 
+	del_timer_sync(&dev_priv->hotplug_reenable_timer);
+
 	if (I915_HAS_HOTPLUG(dev)) {
 		I915_WRITE(PORT_HOTPLUG_EN, 0);
 		I915_WRITE(PORT_HOTPLUG_STAT, I915_READ(PORT_HOTPLUG_STAT));
@@ -3011,6 +3022,8 @@ static void i965_irq_uninstall(struct drm_device * dev)
 	if (!dev_priv)
 		return;
 
+	del_timer_sync(&dev_priv->hotplug_reenable_timer);
+
 	I915_WRITE(PORT_HOTPLUG_EN, 0);
 	I915_WRITE(PORT_HOTPLUG_STAT, I915_READ(PORT_HOTPLUG_STAT));
 
@@ -3026,6 +3039,41 @@ static void i965_irq_uninstall(struct drm_device * dev)
 	I915_WRITE(IIR, I915_READ(IIR));
 }
 
+static void i915_reenable_hotplug_timer_func(unsigned long data)
+{
+	drm_i915_private_t *dev_priv = (drm_i915_private_t *)data;
+	struct drm_device *dev = dev_priv->dev;
+	struct drm_mode_config *mode_config = &dev->mode_config;
+	unsigned long irqflags;
+	int i;
+
+	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+	for (i = (HPD_NONE + 1); i < HPD_NUM_PINS; i++) {
+		struct drm_connector *connector;
+
+		if (dev_priv->hpd_stats[i].hpd_mark != HPD_DISABLED)
+			continue;
+
+		dev_priv->hpd_stats[i].hpd_mark = HPD_ENABLED;
+
+		list_for_each_entry(connector, &mode_config->connector_list, head) {
+			struct intel_connector *intel_connector = to_intel_connector(connector);
+
+			if (intel_connector->encoder->hpd_pin == i) {
+				if (connector->polled != intel_connector->polled)
+					DRM_DEBUG_DRIVER("Reenabling HPD on connector %s\n",
+							 drm_get_connector_name(connector));
+				connector->polled = intel_connector->polled;
+				if (!connector->polled)
+					connector->polled = DRM_CONNECTOR_POLL_HPD;
+			}
+		}
+	}
+	if (dev_priv->display.hpd_irq_setup)
+		dev_priv->display.hpd_irq_setup(dev);
+	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
+}
+
 void intel_irq_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -3038,6 +3086,8 @@ void intel_irq_init(struct drm_device *dev)
 	setup_timer(&dev_priv->gpu_error.hangcheck_timer,
 		    i915_hangcheck_elapsed,
 		    (unsigned long) dev);
+	setup_timer(&dev_priv->hotplug_reenable_timer, i915_reenable_hotplug_timer_func,
+		    (unsigned long) dev_priv);
 
 	pm_qos_add_request(&dev_priv->pm_qos, PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE);