For BSW platform, 
it seems 10ms delay of hot-plug detecting is not enough and to cause high 
fail-rate on old HDMI monitor, and I would like correct it. 

Then user needs to wait screen blank for 2 mins or re-plugin cable (impact to 
user experience).

Thanks for your review.

Gary

-----Original Message-----
From: Wang, Gary C 
Sent: Tuesday, December 15, 2015 12:41 PM
To: intel-gfx@lists.freedesktop.org
Cc: Wang, Gary C <gary.c.w...@intel.com>; Jani Nikula 
<jani.nik...@linux.intel.com>; Daniel Vetter <dan...@ffwll.ch>; Hindman, Gavin 
<gavin.hind...@intel.com>; Jindal, Sonika <sonika.jin...@intel.com>; Sharma, 
Shashank <shashank.sha...@intel.com>
Subject: [PATCH v2] 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.ch...@intel.com>
Tested-by: Gary Wang <gary.c.w...@intel.com>
Cc: Jani Nikula <jani.nik...@linux.intel.com>
Cc: Daniel Vetter <dan...@ffwll.ch>
Cc: Gavin Hindman <gavin.hind...@intel.com>
Cc: Sonika Jindal <sonika.jin...@intel.com>
Cc: Shashank Sharma <shashank.sha...@intel.com>
Signed-off-by: Gary Wang <gary.c.w...@intel.com>
---
 drivers/gpu/drm/i915/intel_hdmi.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)  mode change 100644 => 100755 
drivers/gpu/drm/i915/intel_hdmi.c

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c 
b/drivers/gpu/drm/i915/intel_hdmi.c
old mode 100644
new mode 100755
index 6825543..912d6c3
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1387,17 +1387,18 @@ 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)
+                       mdelay(10);
                live_status = intel_digital_port_connected(dev_priv,
                                hdmi_to_dig_port(intel_hdmi));
-               mdelay(10);
        }
 
        if (!live_status)
--
1.9.1

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