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drm/amd/display: Add a hysteresis to BTR frame multiplier

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[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.

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>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Aric Cyr 2019-03-01 10:24:37 -05:00 committed by Alex Deucher
parent 7fe538a4d6
commit 9070d18f89
1 changed files with 22 additions and 2 deletions
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24
drivers/gpu/drm/amd/display/modules/freesync/freesync.c
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@ -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