[PATCH 02/25] drm/amd/display: DP Compliance 400.1.1 failure

[Bhawanpreet Lakha]

From: abdoulaye berthe <abdoulaye.berthe at amd.com>

[Why]
400.1.1 is failing because we are not performing link training when
we get an HPD pulse for the same display. This is breaking DP
compliance

[How]
Always perform link training after HPD pulse if the detection
reason is not  DETECT_REASON_HPDRX.

Change-Id: I75b0639523105d1b4d9d83180e77b177b420f167
Signed-off-by: abdoulaye berthe <abdoulaye.berthe at amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu at amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link.c | 54 ++++++++++++++-------------
 1 file changed, 28 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index b180197a41e2..5b4f14ad1a6e 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -752,39 +752,41 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
 		if ((prev_sink != NULL) && ((edid_status == EDID_THE_SAME) || (edid_status == EDID_OK)))
 			same_edid = is_same_edid(&prev_sink->dc_edid, &sink->dc_edid);
 
-		// If both edid and dpcd are the same, then discard new sink and revert back to original sink
-		if ((same_edid) && (same_dpcd)) {
-			link_disconnect_remap(prev_sink, link);
-			sink = prev_sink;
-			prev_sink = NULL;
-		} else {
-			if (link->connector_signal == SIGNAL_TYPE_DISPLAY_PORT &&
-					sink_caps.transaction_type ==
-						DDC_TRANSACTION_TYPE_I2C_OVER_AUX) {
-				/*
-				 * TODO debug why Dell 2413 doesn't like
-				 *  two link trainings
-				 */
+		if (link->connector_signal == SIGNAL_TYPE_DISPLAY_PORT &&
+			sink_caps.transaction_type == DDC_TRANSACTION_TYPE_I2C_OVER_AUX &&
+			reason != DETECT_REASON_HPDRX) {
+			/*
+			 * TODO debug why Dell 2413 doesn't like
+			 *  two link trainings
+			 */
 
-				/* deal with non-mst cases */
-				for (i = 0; i < LINK_TRAINING_MAX_VERIFY_RETRY; i++) {
-					int fail_count = 0;
+			/* deal with non-mst cases */
+			for (i = 0; i < LINK_TRAINING_MAX_VERIFY_RETRY; i++) {
+				int fail_count = 0;
 
-					dp_verify_link_cap(link,
-							  &link->reported_link_cap,
-							  &fail_count);
+				dp_verify_link_cap(link,
+						  &link->reported_link_cap,
+						  &fail_count);
 
-					if (fail_count == 0)
-						break;
-				}
+				if (fail_count == 0)
+					break;
 			}
 
-			/* HDMI-DVI Dongle */
-			if (sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A &&
-					!sink->edid_caps.edid_hdmi)
-				sink->sink_signal = SIGNAL_TYPE_DVI_SINGLE_LINK;
+		} else {
+			// If edid is the same, then discard new sink and revert back to original sink
+			if (same_edid) {
+				link_disconnect_remap(prev_sink, link);
+				sink = prev_sink;
+				prev_sink = NULL;
+
+			}
 		}
 
+		/* HDMI-DVI Dongle */
+		if (sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A &&
+				!sink->edid_caps.edid_hdmi)
+			sink->sink_signal = SIGNAL_TYPE_DVI_SINGLE_LINK;
+
 		/* Connectivity log: detection */
 		for (i = 0; i < sink->dc_edid.length / EDID_BLOCK_SIZE; i++) {
 			CONN_DATA_DETECT(link,
-- 
2.14.1