[PATCH 2/2] drm/i915: Perform full detect on sink_count change

[Sivakumar Thulasimani <sivakumar.thulasimani@xxxxxxxxx>]

From: "Thulasimani,Sivakumar" <sivakumar.thulasimani@xxxxxxxxx>

This patch checks for changes in sink_count during short pulse hpd
in check_link_status and forces full detect when sink_count
changes. Compliance test 4.2.2.8 expects this behavior in
compliant driver.

Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@xxxxxxxxx>
---
 drivers/gpu/drm/i915/intel_dp.c  |   24 ++++++++++++++++++------
 drivers/gpu/drm/i915/intel_drv.h |    1 +
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index e4de8e5..04a9ade 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4359,14 +4359,13 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
 	/* If we're HPD-aware, SINK_COUNT changes dynamically */
 	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
 	    intel_dp->downstream_ports[0] & DP_DS_PORT_HPD) {
-		uint8_t reg;
 
 		if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_SINK_COUNT,
-					    &reg, 1) < 0)
+					    &intel_dp->sink_count, 1) < 0)
 			return connector_status_unknown;
 
-		return DP_GET_SINK_COUNT(reg) ? connector_status_connected
-					      : connector_status_disconnected;
+		return DP_GET_SINK_COUNT(intel_dp->sink_count) ?
+		    connector_status_connected : connector_status_disconnected;
 	}
 
 	/* If no HPD, poke DDC gently */
@@ -4401,17 +4400,20 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
  *  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 *need_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;
 	u8 link_status[DP_LINK_STATUS_SIZE];
 
 	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
 
+	*need_full_detect = false;
+
 	/* 4.2.2.8 requires source to read link_status, 0 - 12 DPCD &
 	 * sink_count even for short pulse irrespective of the sink is
 	 * in use or not
@@ -4423,6 +4425,12 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 	if (intel_dp_detect_dpcd(intel_dp) != connector_status_connected)
 		return;
 
+	if (old_sink_count != intel_dp->sink_count) {
+		DRM_ERROR("forcing full detect\n");
+		*need_full_detect = true;
+		return;
+	}
+
 	if (!intel_encoder->base.crtc)
 		return;
 
@@ -5026,13 +5034,17 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 		}
 
 		if (!intel_dp->is_mst) {
+			bool full_detect = false;
 			/*
 			 * 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;
 		}
 	}
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 81b7d77..8aca5bb 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -712,6 +712,7 @@ struct intel_dp {
 	enum hdmi_force_audio force_audio;
 	bool limited_color_range;
 	bool color_range_auto;
+	uint8_t sink_count;
 	uint8_t dpcd[DP_RECEIVER_CAP_SIZE];
 	uint8_t psr_dpcd[EDP_PSR_RECEIVER_CAP_SIZE];
 	uint8_t downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
-- 
1.7.9.5

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