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: Cooper Chiou <cooper.chiou@intel.com>
Tested-by: Gary 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: Gary Wang <gary.c.wang@intel.com>
[danvet: fixup conflict with s/mdelay/msleep/ patch.]
Cc: drm-intel-fixes@lists.freedesktop.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 61fb3980dd396880ffba48523b1e27579868b82b)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 12393df461e4..64086f2d4e26 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/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)