[PATCH] drm/i915: delay hotplug scheduling

[Jani Nikula <jani.nikula@intel.com>]

On some systems we get the hotplug irq on unplug before the DDC pins
have been disconnected, resulting in connector status remaining
connected. Since previous attempts at using hotplug live status before
DDC have failed, the only viable option is to reduce the window for
mistakes. Delay the hotplug processing.

Reference: http://mid.mail-archive.com/CAB4CAwcfj32FovZwpTbekvHpoc3gG0sVbNtW8jeXRcp5qwEsmw@mail.gmail.com
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107125
Reported-by: Chris Chiu <chiu@endlessm.com>
Tested-by: Chris Chiu <chiu@endlessm.com>
Cc: Chris Chiu <chiu@endlessm.com>
Cc: Guang Bai <guang.bai@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h      |  2 +-
 drivers/gpu/drm/i915/intel_hotplug.c | 16 +++++++++++-----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8624b4bdc242..4378be7a20d5 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -286,7 +286,7 @@ enum hpd_pin {
 #define HPD_STORM_DEFAULT_THRESHOLD 5
 
 struct i915_hotplug {
-	struct work_struct hotplug_work;
+	struct delayed_work hotplug_work;
 
 	struct {
 		unsigned long last_jiffies;
diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
index 648a13c6043c..ce9bedbedcd1 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -110,6 +110,9 @@ enum hpd_pin intel_hpd_pin_default(struct drm_i915_private *dev_priv,
 	}
 }
 
+/* Delay between irq and hotplug detect processing */
+#define HOTPLUG_DELAY_MS		300
+
 #define HPD_STORM_DETECT_PERIOD		1000
 #define HPD_STORM_REENABLE_DELAY	(2 * 60 * 1000)
 
@@ -319,7 +322,8 @@ static void i915_digport_work_func(struct work_struct *work)
 		spin_lock_irq(&dev_priv->irq_lock);
 		dev_priv->hotplug.event_bits |= old_bits;
 		spin_unlock_irq(&dev_priv->irq_lock);
-		schedule_work(&dev_priv->hotplug.hotplug_work);
+		schedule_delayed_work(&dev_priv->hotplug.hotplug_work,
+				      msecs_to_jiffies(HOTPLUG_DELAY_MS));
 	}
 }
 
@@ -329,7 +333,7 @@ static void i915_digport_work_func(struct work_struct *work)
 static void i915_hotplug_work_func(struct work_struct *work)
 {
 	struct drm_i915_private *dev_priv =
-		container_of(work, struct drm_i915_private, hotplug.hotplug_work);
+		container_of(work, struct drm_i915_private, hotplug.hotplug_work.work);
 	struct drm_device *dev = &dev_priv->drm;
 	struct intel_connector *intel_connector;
 	struct intel_encoder *intel_encoder;
@@ -466,7 +470,8 @@ void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
 	if (queue_dig)
 		queue_work(dev_priv->hotplug.dp_wq, &dev_priv->hotplug.dig_port_work);
 	if (queue_hp)
-		schedule_work(&dev_priv->hotplug.hotplug_work);
+		schedule_delayed_work(&dev_priv->hotplug.hotplug_work,
+				      msecs_to_jiffies(HOTPLUG_DELAY_MS));
 }
 
 /**
@@ -586,7 +591,8 @@ void intel_hpd_poll_init(struct drm_i915_private *dev_priv)
 
 void intel_hpd_init_work(struct drm_i915_private *dev_priv)
 {
-	INIT_WORK(&dev_priv->hotplug.hotplug_work, i915_hotplug_work_func);
+	INIT_DELAYED_WORK(&dev_priv->hotplug.hotplug_work,
+			  i915_hotplug_work_func);
 	INIT_WORK(&dev_priv->hotplug.dig_port_work, i915_digport_work_func);
 	INIT_WORK(&dev_priv->hotplug.poll_init_work, i915_hpd_poll_init_work);
 	INIT_DELAYED_WORK(&dev_priv->hotplug.reenable_work,
@@ -604,7 +610,7 @@ void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 	spin_unlock_irq(&dev_priv->irq_lock);
 
 	cancel_work_sync(&dev_priv->hotplug.dig_port_work);
-	cancel_work_sync(&dev_priv->hotplug.hotplug_work);
+	cancel_delayed_work_sync(&dev_priv->hotplug.hotplug_work);
 	cancel_work_sync(&dev_priv->hotplug.poll_init_work);
 	cancel_delayed_work_sync(&dev_priv->hotplug.reenable_work);
 }
-- 
2.11.0

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