drm/i915: get runtime PM while trying to detect CRT

Otherwise we'll read registers that return 0xffffffff, trigger some
WARNs, think CRT is actually connected (because certain bits are 1),
and fail the drm-resources-equal testcase!

Tested on a SNB machine with runtime PM support (which is not upstream
yet, but is already on my public tree at freedesktop.org, and will
hopefully eventually become upstream).

Testcase: igt/pm_pc8/drm-resources-equal
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_crt.c

@@ -630,10 +630,13 @@ static enum drm_connector_status
 intel_crt_detect(struct drm_connector *connector, bool force)
 {
 	struct drm_device *dev = connector->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_crt *crt = intel_attached_crt(connector);
 	enum drm_connector_status status;
 	struct intel_load_detect_pipe tmp;
 
+	intel_runtime_pm_get(dev_priv);
+
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
 		      connector->base.id, drm_get_connector_name(connector),
 		      force);
@@ -645,23 +648,30 @@ intel_crt_detect(struct drm_connector *connector, bool force)
 		 */
 		if (intel_crt_detect_hotplug(connector)) {
 			DRM_DEBUG_KMS("CRT detected via hotplug\n");
-			return connector_status_connected;
+			status = connector_status_connected;
+			goto out;
 		} else
 			DRM_DEBUG_KMS("CRT not detected via hotplug\n");
 	}
 
-	if (intel_crt_detect_ddc(connector))
-		return connector_status_connected;
+	if (intel_crt_detect_ddc(connector)) {
+		status = connector_status_connected;
+		goto out;
+	}
 
 	/* Load detection is broken on HPD capable machines. Whoever wants a
 	 * broken monitor (without edid) to work behind a broken kvm (that fails
 	 * to have the right resistors for HP detection) needs to fix this up.
 	 * For now just bail out. */
-	if (I915_HAS_HOTPLUG(dev))
-		return connector_status_disconnected;
+	if (I915_HAS_HOTPLUG(dev)) {
+		status = connector_status_disconnected;
+		goto out;
+	}
 
-	if (!force)
-		return connector->status;
+	if (!force) {
+		status = connector->status;
+		goto out;
+	}
 
 	/* for pre-945g platforms use load detect */
 	if (intel_get_load_detect_pipe(connector, NULL, &tmp)) {
@@ -673,6 +683,8 @@ intel_crt_detect(struct drm_connector *connector, bool force)
 	} else
 		status = connector_status_unknown;
 
+out:
+	intel_runtime_pm_put(dev_priv);
 	return status;
 }