[Intel-gfx] [PATCH] drm/i915: Correct max delay for HDMI hotplug live status checking

[Wang, Gary C]

Hi Sonika,

Thanks for your comment, and it's more readability on code.

But it only delay 2 integration of each 10ms among checking hot-plug with 3 times. Could I change it to following snippet code to read hotplug_status 4 times at most for 3 integration 10ms delay?

	unsigned int retry = 3;	

	do {
		live_status = intel_digital_port_connected(dev_priv,
				hdmi_to_dig_port(intel_hdmi));
		if (live_status || !retry)
			break;
		mdelay(10);
	} while (retry--);

Thanks!

Gary

-----Original Message-----
From: Jindal, Sonika 
Sent: Friday, December 11, 2015 1:05 PM
To: Wang, Gary C <gary.c.wang at intel.com>; intel-gfx at lists.freedesktop.org
Subject: RE: [Intel-gfx] [PATCH] drm/i915: Correct max delay for HDMI hotplug live status checking

How about following instead of two levels of check in the while loop:

unsigned int retry = 3;

do {
	live_status = intel_digital_port_connected(dev_priv,
			hdmi_to_dig_port(intel_hdmi));
	if (live_status)
		break;
	mdelay(10);
} while (--retry);

Regards,
Sonika

-----Original Message-----
From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of Wang, Gary C
Sent: Friday, December 11, 2015 7:39 AM
To: intel-gfx at lists.freedesktop.org
Subject: [Intel-gfx] [PATCH] drm/i915: Correct max delay for HDMI hotplug live status checking

The total delay of HDMI hotplug detecting with 30ms should have 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.

Reviewed-by: Cooper Chiou <cooper.chiou at intel.com>
Cc: Gavin Hindman <gavin.hindman at intel.com>
Signed-off-by: Gary Wang <gary.c.wang at intel.com>
---
 drivers/gpu/drm/i915/intel_hdmi.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 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 be7fab9..888401b
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1387,16 +1387,19 @@ 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;
+	// read hotplug status 4 times at most for 30ms delay (3 retries of 10ms each)
+	unsigned int retry = 4;
 
 	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) {
+	while (!live_status && retry--) {
 		live_status = intel_digital_port_connected(dev_priv,
 				hdmi_to_dig_port(intel_hdmi));
+		if (live_status || !retry)
+				break;
 		mdelay(10);
 	}
 
--
1.9.1

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