For my test on this issue, it only got high fail-rate with some specific HDMI 
monitors. 

It’s also not easy to reproduce it by modern HDMI monitors (with 1080p/2K/4K 
resolutions…etc.) or will get low fail-rat (e.g. 1/50 failed test) with that 
ones. So Linux BSW Gfx validation team could also suffer being hard to 
reproduce it.

I just would like to raise this problem (about HDMI compatibility) and collect 
practical cases for handling this kind of issue more smoothly.

Thanks!

Gary

-----Original Message-----
From: Intel-gfx [mailto:[email protected]] On Behalf Of 
Gary Wang
Sent: Wednesday, December 23, 2015 4:12 PM
To: [email protected]
Cc: Kumar, Shobhit <[email protected]>
Subject: [Intel-gfx] [PATCH] drm/i915: increase the tries for HDMI hotplug live 
status checking

The total delay of HDMI hotplug detecting with 30ms is sometimes not enoughtfor 
HDMI live status up with specific HDMI monitors in BSW platform.

After doing experiments for following monitors, it needs 80ms at least for 
those worst cases.

Lenovo L246 1xwA (4 failed, necessary hot-plug delay: 58/40/60/40ms) Philips 
HH2AP (9 failed, necessary hot-plug delay: 80/50/50/60/46/40/58/58/39ms) BENQ 
ET-0035-N (6 failed, necessary hot-plug delay: 60/50/50/80/80/40ms) DELL 
U2713HM (2 failed, necessary hot-plug delay: 58/59ms) HP HP-LP2475w (5 failed, 
necessary hot-plug delay: 70/50/40/60/40ms)

It looks like 70-80 ms is BSW platform needs in some bad cases of the monitors 
at this end (8 times delay at most). Keep less than 100ms for HDCP pulse HPD 
low (with at least 100ms) to respond a plug out.

Reviewed-by: Cooper Chiou <[email protected]>
Tested-by: Gary Wang <[email protected]>
Cc: Gavin Hindman <[email protected]>
Cc: Sonika Jindal <[email protected]>
Cc: Shashank Sharma <[email protected]>
Cc: Shobhit Kumar <[email protected]>
Signed-off-by: Gary Wang <[email protected]>
---
 drivers/gpu/drm/i915/intel_hdmi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)  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 6214175..4a77639
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1392,7 +1392,7 @@ intel_hdmi_detect(struct drm_connector *connector, bool 
force)
 
        intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
 
-       for (try = 0; !live_status && try < 4; try++) {
+       for (try = 0; !live_status && try < 9; try++) {
                if (try)
                        msleep(10);
                live_status = intel_digital_port_connected(dev_priv,
--
1.9.1

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