[Intel-gfx] [PATCH] drm/i915: Restrict usage of live status check

[Shashank Sharma]

This patch restricts usage of live status check for HDMI detection.
While testing certain (monitor + cable) combinations with various
intel  platforms, it seems that live status register is not reliable
on some older devices. So limit the live_status check from VLV onwards.

This fixes a regression introduced in:
	commit: 237ed86 "drm/i915: Check live status"
	Author: Sonika Jindal <sonika.jindal at intel.com>
	Date:   Tue Sep 15 09:44:20 2015 +0530

Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
---
 drivers/gpu/drm/i915/intel_hdmi.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index e2dab48..d24d18a 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1397,7 +1397,8 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
 	enum drm_connector_status status;
 	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 	struct drm_i915_private *dev_priv = to_i915(connector->dev);
-	bool live_status = false;
+	struct drm_device *dev = connector->dev;
+	bool live_status = true;
 	unsigned int try;
 
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
@@ -1405,16 +1406,21 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
 
 	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
 
-	for (try = 0; !live_status && try < 9; try++) {
-		if (try)
-			msleep(10);
-		live_status = intel_digital_port_connected(dev_priv,
+	/*
+	* Live status check for HDMI detection is not very
+	* reliable on older platforms. So insist the live
+	* status check for EDID read from VLV onwards.
+	*/
+	if (INTEL_INFO(dev)->gen >= 7 && !IS_IVYBRIDGE(dev)) {
+		for (try = 0; !live_status && try < 9; try++) {
+			if (try)
+				msleep(10);
+			live_status = intel_digital_port_connected(dev_priv,
 				hdmi_to_dig_port(intel_hdmi));
+		}
+		DRM_DEBUG_KMS("Live status %s\n", live_status ? "up" : "down");
 	}
 
-	if (!live_status)
-		DRM_DEBUG_KMS("Live status not up!");
-
 	intel_hdmi_unset_edid(connector);
 
 	if (intel_hdmi_set_edid(connector, live_status)) {
-- 
1.9.1