From: Andrew Jiang <Andrew.Jiang@amd.com>
Date: Wed, 4 Oct 2017 15:55:45 -0400
Subject: drm/amd/display: Fix up plane_states add/remove logic
Git-commit: abb4986eea1670922a0b89ef62688b4b649bd3c6
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Our plane_states array trimming logic was faulty, we should be starting
to shuffle from the plane that was just released, not from the very
beginning of the array.

Also get rid of a leftover line that was setting the plane state at the
stream index to null, leading to issues. Also move the
dc_plane_state_retain call to where we reference plane_state, in case we
do hit the error case where we can't get a free pipe.

Signed-off-by: Andrew Jiang <Andrew.Jiang@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/dc/core/dc_resource.c |   13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -1073,9 +1073,6 @@ bool dc_add_plane_to_context(
 		return false;
 	}
 
-	/* retain new surfaces */
-	dc_plane_state_retain(plane_state);
-
 	free_pipe = acquire_free_pipe_for_stream(context, pool, stream);
 
 #if defined(CONFIG_DRM_AMD_DC_DCN1_0)
@@ -1085,11 +1082,11 @@ bool dc_add_plane_to_context(
 			free_pipe = &context->res_ctx.pipe_ctx[pipe_idx];
 	}
 #endif
-	if (!free_pipe) {
-		stream_status->plane_states[i] = NULL;
+	if (!free_pipe)
 		return false;
-	}
 
+	/* retain new surfaces */
+	dc_plane_state_retain(plane_state);
 	free_pipe->plane_state = plane_state;
 
 	if (head_pipe != free_pipe) {
@@ -1181,8 +1178,8 @@ bool dc_remove_plane_from_context(
 
 	stream_status->plane_count--;
 
-	/* Trim back arrays */
-	for (i = 0; i < stream_status->plane_count; i++)
+	/* Start at the plane we've just released, and move all the planes one index forward to "trim" the array */
+	for (; i < stream_status->plane_count; i++)
 		stream_status->plane_states[i] = stream_status->plane_states[i + 1];
 
 	stream_status->plane_states[stream_status->plane_count] = NULL;