drm/i915: Correct max delay for HDMI hotplug live status checking

The total delay of HDMI hotplug detecting with 30ms have already
been split into a resolution of 3 retries of 10ms each, for the worst
cases. But it still suffered from only waiting 10ms at most in
intel_hdmi_detect(). This patch corrects it by reading hotplug status
with 4 times at most for 30ms delay.

v2:
- straight up to loop execution for more clear in code readability
- mdelay will replace with msleep by Daniel's new patch

	drm/i915: mdelay(10) considered harmful

- suggest to re-evaluate try times for being compatible to old HDMI monitor
Reviewed-by: NCooper Chiou <cooper.chiou@intel.com>
Tested-by: NGary Wang <gary.c.wang@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Gavin Hindman <gavin.hindman@intel.com>
Cc: Sonika Jindal <sonika.jindal@intel.com>
Cc: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: NGary Wang <gary.c.wang@intel.com>
[danvet: fixup conflict with s/mdelay/msleep/ patch.]
Cc: drm-intel-fixes@lists.freedesktop.org
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 61fb3980)
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_hdmi.c

@@ -1374,17 +1374,18 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
 	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 retry = 3;
+	unsigned int try;
 
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
 		      connector->base.id, connector->name);
 
 	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
 
-	while (!live_status && --retry) {
+	for (try = 0; !live_status && try < 4; try++) {
+		if (try)
+			msleep(10);
 		live_status = intel_digital_port_connected(dev_priv,
 				hdmi_to_dig_port(intel_hdmi));
-		msleep(10);
 	}
 
 	if (!live_status)