From: Eric Cook <Eric.Cook@amd.com>
Date: Wed, 26 Apr 2017 11:51:38 -0400
Subject: drm/amd/display: Check for Zero Range in FreeSync Calc
Git-commit: 7cc9e7a68abef8d1303700bac6f58ab76bc9db7b
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

-check for min/max range in freesync calculation and handle it accordingly

Signed-off-by: Eric <eric.cook@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/display/modules/freesync/freesync.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -363,6 +363,21 @@ static void calc_freesync_range(struct c
 	unsigned int index = map_index_from_stream(core_freesync, stream);
 	uint32_t vtotal = stream->timing.v_total;
 
+	if ((min_refresh_in_uhz == 0) || (max_refresh_in_uhz == 0)) {
+		state->freesync_range.min_refresh =
+				state->nominal_refresh_rate_in_micro_hz;
+		state->freesync_range.max_refresh =
+				state->nominal_refresh_rate_in_micro_hz;
+
+		state->freesync_range.max_frame_duration = 0;
+		state->freesync_range.min_frame_duration = 0;
+
+		state->freesync_range.vmax = vtotal;
+		state->freesync_range.vmin = vtotal;
+
+		return;
+	}
+
 	min_frame_duration_in_ns = ((unsigned int) (div64_u64(
 					(1000000000ULL * 1000000),
 					max_refresh_in_uhz)));