[PATCH 24/73] drm/amd/display: fix MST link training fail division by 0

[Harry Wentland]

From: Eric Yang <Eric.Yang2 at amd.com>

When link training fail in MST case, we will divide by 0
when calculating avg_time_slots_per_mtp, so we cannot
proceed.

Change-Id: Iae7aef320deb3c204f3450544c36f89b075a5c21
Signed-off-by: Eric Yang <Eric.Yang2 at amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland at amd.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 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 3b394a5f1c66..7b0e43c0685c 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -2386,9 +2386,11 @@ void core_link_enable_stream(
 
 			/* Abort stream enable *unless* the failure was due to
 			 * DP link training - some DP monitors will recover and
-			 * show the stream anyway.
+			 * show the stream anyway. But MST displays can't proceed
+			 * without link training.
 			 */
-			if (status != DC_FAIL_DP_LINK_TRAINING) {
+			if (status != DC_FAIL_DP_LINK_TRAINING ||
+					pipe_ctx->stream->signal == SIGNAL_TYPE_DISPLAY_PORT_MST) {
 				BREAK_TO_DEBUGGER();
 				return;
 			}
-- 
2.14.1