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

[Shashank Sharma]

This patch does the following:
- 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
  doesn't work reliably on some older devices. So limit the
  live_status check for HDMI detection, only for platforms
  from gen7 onwards.
- Cleans up the retry logic.
  There is an extra 'if (try)' check, which can be avoided by
  changing the logic slightly, keeping the delay as same(80ms)

Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
---
 drivers/gpu/drm/i915/intel_hdmi.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index e2dab48..3f6db91 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1397,24 +1397,31 @@ 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;
-	unsigned int try;
+	bool live_status = true;
+	unsigned int try = 9;
 
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
 		      connector->base.id, connector->name);
 
 	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
 
-	for (try = 0; !live_status && try < 9; try++) {
-		if (try)
-			msleep(10);
+	/*
+	 * When tested with specific set of monitors + cables,
+	 * live status behavior is not very consistent for older
+	 * platforms. So add live status check from GEN7
+	 * onwards.
+	 */
+	if (INTEL_INFO(dev_priv->dev)->gen >= 7) {
+retry_ls:
 		live_status = intel_digital_port_connected(dev_priv,
 				hdmi_to_dig_port(intel_hdmi));
+		if (!live_status && --try) {
+			msleep(10);
+			goto retry_ls;
+		}
+		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