From: Harry Wentland <harry.wentland@amd.com>
Date: Thu, 7 Dec 2017 14:09:15 -0500
Subject: drm/amd/display: Debug print when validate_stream fails
Git-commit: a39438f0b9261a249da6d5957c03e1fab699f467
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

It might be good to understand why validate fails.

Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2827,6 +2827,7 @@ int amdgpu_dm_connector_mode_valid(struc
 	/* TODO: Unhardcode stream count */
 	struct dc_stream_state *stream;
 	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
+	enum dc_status dc_result = DC_OK;
 
 	if ((mode->flags & DRM_MODE_FLAG_INTERLACE) ||
 			(mode->flags & DRM_MODE_FLAG_DBLSCAN))
@@ -2859,8 +2860,15 @@ int amdgpu_dm_connector_mode_valid(struc
 	stream->src.height = mode->vdisplay;
 	stream->dst = stream->src;
 
-	if (dc_validate_stream(adev->dm.dc, stream) == DC_OK)
+	dc_result = dc_validate_stream(adev->dm.dc, stream);
+
+	if (dc_result == DC_OK)
 		result = MODE_OK;
+	else
+		DRM_DEBUG_KMS("Mode %dx%d (clk %d) failed DC validation\n",
+			      mode->vdisplay,
+			      mode->hdisplay,
+			      mode->clock);
 
 	dc_stream_release(stream);