drm/i915: add ValleyView specific CRT detect function

Might be able to merge this back in at some point, but we're seeing bugs
with ADPA based detection, so keep it separate for now with explicit
hotplug trigger usage.

v2: drop superfluous debug message
v3: comment forced detection, need to debug (Eugeni)
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_crt.c

@@ -230,6 +230,42 @@ static bool intel_ironlake_crt_detect_hotplug(struct drm_connector *connector)
 	return ret;
 }
 
+static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 adpa;
+	bool ret;
+	u32 save_adpa;
+
+	save_adpa = adpa = I915_READ(ADPA);
+	DRM_DEBUG_KMS("trigger hotplug detect cycle: adpa=0x%x\n", adpa);
+
+	adpa |= ADPA_CRT_HOTPLUG_FORCE_TRIGGER;
+
+	I915_WRITE(ADPA, adpa);
+
+	if (wait_for((I915_READ(ADPA) & ADPA_CRT_HOTPLUG_FORCE_TRIGGER) == 0,
+		     1000)) {
+		DRM_DEBUG_KMS("timed out waiting for FORCE_TRIGGER");
+		I915_WRITE(ADPA, save_adpa);
+	}
+
+	/* Check the status to see if both blue and green are on now */
+	adpa = I915_READ(ADPA);
+	if ((adpa & ADPA_CRT_HOTPLUG_MONITOR_MASK) != 0)
+		ret = true;
+	else
+		ret = false;
+
+	DRM_DEBUG_KMS("valleyview hotplug adpa=0x%x, result %d\n", adpa, ret);
+
+	/* FIXME: debug force function and remove */
+	ret = true;
+
+	return ret;
+}
+
 /**
  * Uses CRT_HOTPLUG_EN and CRT_HOTPLUG_STAT to detect CRT presence.
  *
@@ -249,6 +285,9 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
 	if (HAS_PCH_SPLIT(dev))
 		return intel_ironlake_crt_detect_hotplug(connector);
 
+	if (IS_VALLEYVIEW(dev))
+		return valleyview_crt_detect_hotplug(connector);
+
 	/*
 	 * On 4 series desktop, CRT detect sequence need to be done twice
 	 * to get a reliable result.