[Intel-gfx] [PATCH 4/4] drm/i915: force full detect on sink count change

[Sivakumar Thulasimani]

From: "Thulasimani,Sivakumar" <sivakumar.thulasimani at intel.com>

This patch checks for changes in sink count between short pulse
hpds and forces full detect when there is a change.

This will allow both detection of hotplug and unplug of panels
through dongles that give only short pulse for such events.

v2: changed variable type from u8 to bool (Jani)
    return immediately if perform_full_detect is set(Siva)

Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c |   27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 834f513..279e52c 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4370,26 +4370,39 @@ go_again:
  *  4. Check link status on receipt of hot-plug interrupt
  */
 static void
-intel_dp_check_link_status(struct intel_dp *intel_dp)
+intel_dp_check_link_status(struct intel_dp *intel_dp, bool *perform_full_detect)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
 	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
 	struct intel_crtc *crtc =
 		to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
 	u8 sink_irq_vector;
+	u8 old_sink_count = intel_dp->sink_count;
+	bool ret;
 	u8 link_status[DP_LINK_STATUS_SIZE];
 
 	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
 
+	*perform_full_detect = false;
+
 	/* Try to read receiver status if the link appears to be up */
 	if (!intel_dp_get_link_status(intel_dp, link_status)) {
 		return;
 	}
 
-	/* Now read the DPCD to see if it's actually running */
-	if (!intel_dp_get_dpcd(intel_dp)) {
+	/* Now read the DPCD to see if it's actually running
+	 * Don't return immediately if dpcd read failed,
+	 * if sink count was 1 and dpcd read failed we need
+	 * to do full detection
+	 */
+	ret = intel_dp_get_dpcd(intel_dp);
+
+	if (old_sink_count != intel_dp->sink_count)
+		*perform_full_detect = true;
+
+	/* No need to proceed if we are going to do full detect */
+	if (!ret || *perform_full_detect)
 		return;
-	}
 
 	if (!intel_encoder->base.crtc)
 		return;
@@ -5031,13 +5044,17 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 		}
 
 		if (!intel_dp->is_mst) {
+			bool full_detect;
 			/*
 			 * we'll check the link status via the normal hot plug path later -
 			 * but for short hpds we should check it now
 			 */
 			drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
-			intel_dp_check_link_status(intel_dp);
+			intel_dp_check_link_status(intel_dp, &full_detect);
 			drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+			if (full_detect)
+				goto put_power;
 		}
 	}
 
-- 
1.7.9.5