[Intel-gfx] [PATCH] drm/i915: increase the tries for HDMI hotplug live status checking

Wang, Gary C gary.c.wang at intel.com
Wed Dec 23 00:30:13 PST 2015

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.



-----Original Message-----
From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of Gary Wang
Sent: Wednesday, December 23, 2015 4:12 PM
To: intel-gfx at lists.freedesktop.org
Cc: Kumar, Shobhit <shobhit.kumar at intel.com>
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 <cooper.chiou at intel.com>
Tested-by: Gary Wang <gary.c.wang at intel.com>
Cc: Gavin Hindman <gavin.hindman at intel.com>
Cc: Sonika Jindal <sonika.jindal at intel.com>
Cc: Shashank Sharma <shashank.sharma at intel.com>
Cc: Shobhit Kumar <shobhit.kumar at intel.com>
Signed-off-by: Gary Wang <gary.c.wang at intel.com>
 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)
 		live_status = intel_digital_port_connected(dev_priv,

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