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From 014398385e1a5962d508442782a6a60429341b72 Mon Sep 17 00:00:00 2001
From: Aric Cyr <aric.cyr@amd.com>
Date: Fri, 1 Mar 2019 10:24:37 -0500
Subject: [PATCH 1638/2940] drm/amd/display: Add a hysteresis to BTR frame
multiplier
[Why]
Flickering is observed on some displays when the number of inserted BTR
frames changes frequently.
[How]
Add in a margin of drift to prevent the inserted number of frames from
jumping around too frequently.
Change-Id: I592ce229f93faa74b5baa2e43a89c9e5a6174103
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
---
.../amd/display/modules/freesync/freesync.c | 24 +++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
index bfd27f10879e..5f493e9d6bbb 100644
--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -37,6 +37,8 @@
#define RENDER_TIMES_MAX_COUNT 10
/* Threshold to exit BTR (to avoid frequent enter-exits at the lower limit) */
#define BTR_EXIT_MARGIN 2000
+/* Threshold to change BTR multiplier (to avoid frequent changes) */
+#define BTR_DRIFT_MARGIN 2000
/*Threshold to exit fixed refresh rate*/
#define FIXED_REFRESH_EXIT_MARGIN_IN_HZ 4
/* Number of consecutive frames to check before entering/exiting fixed refresh*/
@@ -248,6 +250,7 @@ static void apply_below_the_range(struct core_freesync *core_freesync,
unsigned int frames_to_insert = 0;
unsigned int min_frame_duration_in_ns = 0;
unsigned int max_render_time_in_us = in_out_vrr->max_duration_in_us;
+ unsigned int delta_from_mid_point_delta_in_us;
min_frame_duration_in_ns = ((unsigned int) (div64_u64(
(1000000000ULL * 1000000),
@@ -318,10 +321,27 @@ static void apply_below_the_range(struct core_freesync *core_freesync,
/* Choose number of frames to insert based on how close it
* can get to the mid point of the variable range.
*/
- if (delta_from_mid_point_in_us_1 < delta_from_mid_point_in_us_2)
+ if (delta_from_mid_point_in_us_1 < delta_from_mid_point_in_us_2) {
frames_to_insert = mid_point_frames_ceil;
- else
+ delta_from_mid_point_delta_in_us = delta_from_mid_point_in_us_2 -
+ delta_from_mid_point_in_us_1;
+ } else {
frames_to_insert = mid_point_frames_floor;
+ delta_from_mid_point_delta_in_us = delta_from_mid_point_in_us_1 -
+ delta_from_mid_point_in_us_2;
+ }
+
+ /* Prefer current frame multiplier when BTR is enabled unless it drifts
+ * too far from the midpoint
+ */
+ if (in_out_vrr->btr.frames_to_insert != 0 &&
+ delta_from_mid_point_delta_in_us < BTR_DRIFT_MARGIN) {
+ if (((last_render_time_in_us / in_out_vrr->btr.frames_to_insert) <
+ in_out_vrr->max_duration_in_us) &&
+ ((last_render_time_in_us / in_out_vrr->btr.frames_to_insert) >
+ in_out_vrr->min_duration_in_us))
+ frames_to_insert = in_out_vrr->btr.frames_to_insert;
+ }
/* Either we've calculated the number of frames to insert,
* or we need to insert min duration frames
--
2.17.1
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