drm/i915: s/hotplug_irq_storm_detect/intel_hpd_irq_handler/

The combination of Paulo's fifo underrun detection code and Egbert's
hpd storm handling code unfortunately made the hpd storm handling code
racy.

To avoid duplicating tricky interrupt locking code over all platforms
start with a bit of refactoring. This patch is the very first step
since in the end the irq storm handling code will handle all hotplug
logic (and so also encapsulate the locking nicely).

v2: Rebase on top of the i965g/gm sdvo hpd fix.

Cc: Egbert Eich <eich@suse.de>
Reviewed-by: Egbert Eich <eich@suse.de>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -875,7 +875,7 @@ static void gen6_queue_rps_work(struct drm_i915_private *dev_priv,
 #define HPD_STORM_DETECT_PERIOD 1000
 #define HPD_STORM_THRESHOLD 5
 
-static inline bool hotplug_irq_storm_detect(struct drm_device *dev,
+static inline bool intel_hpd_irq_handler(struct drm_device *dev,
 					 u32 hotplug_trigger,
 					 const u32 *hpd)
 {
@@ -1018,7 +1018,7 @@ static irqreturn_t valleyview_irq_handler(int irq, void *arg)
 			DRM_DEBUG_DRIVER("hotplug event received, stat 0x%08x\n",
 					 hotplug_status);
 			if (hotplug_trigger) {
-				if (hotplug_irq_storm_detect(dev, hotplug_trigger, hpd_status_i915))
+				if (intel_hpd_irq_handler(dev, hotplug_trigger, hpd_status_i915))
 					i915_hpd_irq_setup(dev);
 				queue_work(dev_priv->wq,
 					   &dev_priv->hotplug_work);
@@ -1049,7 +1049,7 @@ static void ibx_irq_handler(struct drm_device *dev, u32 pch_iir)
 	u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK;
 
 	if (hotplug_trigger) {
-		if (hotplug_irq_storm_detect(dev, hotplug_trigger, hpd_ibx))
+		if (intel_hpd_irq_handler(dev, hotplug_trigger, hpd_ibx))
 			ibx_hpd_irq_setup(dev);
 		queue_work(dev_priv->wq, &dev_priv->hotplug_work);
 	}
@@ -1154,7 +1154,7 @@ static void cpt_irq_handler(struct drm_device *dev, u32 pch_iir)
 	u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK_CPT;
 
 	if (hotplug_trigger) {
-		if (hotplug_irq_storm_detect(dev, hotplug_trigger, hpd_cpt))
+		if (intel_hpd_irq_handler(dev, hotplug_trigger, hpd_cpt))
 			ibx_hpd_irq_setup(dev);
 		queue_work(dev_priv->wq, &dev_priv->hotplug_work);
 	}
@@ -3232,7 +3232,7 @@ static irqreturn_t i915_irq_handler(int irq, void *arg)
 			DRM_DEBUG_DRIVER("hotplug event received, stat 0x%08x\n",
 				  hotplug_status);
 			if (hotplug_trigger) {
-				if (hotplug_irq_storm_detect(dev, hotplug_trigger, hpd_status_i915))
+				if (intel_hpd_irq_handler(dev, hotplug_trigger, hpd_status_i915))
 					i915_hpd_irq_setup(dev);
 				queue_work(dev_priv->wq,
 					   &dev_priv->hotplug_work);
@@ -3473,7 +3473,7 @@ static irqreturn_t i965_irq_handler(int irq, void *arg)
 			DRM_DEBUG_DRIVER("hotplug event received, stat 0x%08x\n",
 				  hotplug_status);
 			if (hotplug_trigger) {
-				if (hotplug_irq_storm_detect(dev, hotplug_trigger,
+				if (intel_hpd_irq_handler(dev, hotplug_trigger,
 							    IS_G4X(dev) ? hpd_status_gen4 : hpd_status_i915))
 					i915_hpd_irq_setup(dev);
 				queue_work(dev_priv->wq,