Commit bb2746ac authored by Aric Cyr's avatar Aric Cyr Committed by Alex Deucher
Browse files

drm/amd/display: Improve LFC behaviour 



[Why]
There can be some unsynchronized frames when entering/exiting
LFC.  This may cause tearing or stuttering at such transitions.

[How]
Add a enter/exit margin to algorithm to smoothly transition into
and out of LFC without desynchronizing frames.

Signed-off-by: default avatarAric Cyr <aric.cyr@amd.com>
Reviewed-by: default avatarReza Amini <Reza.Amini@amd.com>
Acked-by: default avatarLeo Li <sunpeng.li@amd.com>
Acked-by: default avatarSivapiriyan Kumarasamy <Sivapiriyan.Kumarasamy@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent ec4388a2

drivers/gpu/drm/amd/display/modules/freesync/freesync.c

+19 −13
Original line number Diff line number Diff line
@@ -37,8 +37,8 @@ 
#define STATIC_SCREEN_RAMP_DELTA_REFRESH_RATE_PER_FRAME ((1000 / 60) * 65)

/* Number of elements in the render times cache array */

#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 exit/exit BTR (to avoid frequent enter-exits at the lower limit) */

#define BTR_MAX_MARGIN 2500

/* Threshold to change BTR multiplier (to avoid frequent changes) */

#define BTR_DRIFT_MARGIN 2000

/*Threshold to exit fixed refresh rate*/
@@ -250,25 +250,23 @@ static void apply_below_the_range(struct core_freesync *core_freesync, 
	unsigned int delta_from_mid_point_in_us_1 = 0xFFFFFFFF;

	unsigned int delta_from_mid_point_in_us_2 = 0xFFFFFFFF;

	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),

		in_out_vrr->max_refresh_in_uhz)));

	unsigned int max_render_time_in_us =

			in_out_vrr->max_duration_in_us - in_out_vrr->btr.margin_in_us;



	/* Program BTR */

	if (last_render_time_in_us + BTR_EXIT_MARGIN < max_render_time_in_us) {

	if ((last_render_time_in_us + in_out_vrr->btr.margin_in_us / 2) < max_render_time_in_us) {

		/* Exit Below the Range */

		if (in_out_vrr->btr.btr_active) {

			in_out_vrr->btr.frame_counter = 0;

			in_out_vrr->btr.btr_active = false;

		}

	} else if (last_render_time_in_us > max_render_time_in_us) {

	} else if (last_render_time_in_us > (max_render_time_in_us + in_out_vrr->btr.margin_in_us / 2)) {

		/* Enter Below the Range */

		if (!in_out_vrr->btr.btr_active) {

			in_out_vrr->btr.btr_active = true;

		}

	}



	/* BTR set to "not active" so disengage */

	if (!in_out_vrr->btr.btr_active) {
@@ -323,7 +321,9 @@ 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 ((frame_time_in_us / mid_point_frames_ceil) > in_out_vrr->min_duration_in_us &&

				(delta_from_mid_point_in_us_1 < delta_from_mid_point_in_us_2 ||

						mid_point_frames_floor < 2)) {

			frames_to_insert = mid_point_frames_ceil;

			delta_from_mid_point_delta_in_us = delta_from_mid_point_in_us_2 -

					delta_from_mid_point_in_us_1;
@@ -339,7 +339,7 @@ static void apply_below_the_range(struct core_freesync *core_freesync, 
		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) &&

					max_render_time_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;
@@ -788,6 +788,11 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync, 
		refresh_range = in_out_vrr->max_refresh_in_uhz -

				in_out_vrr->min_refresh_in_uhz;



		in_out_vrr->btr.margin_in_us = in_out_vrr->max_duration_in_us -

				2 * in_out_vrr->min_duration_in_us;

		if (in_out_vrr->btr.margin_in_us > BTR_MAX_MARGIN)

			in_out_vrr->btr.margin_in_us = BTR_MAX_MARGIN;



		in_out_vrr->supported = true;

	}
@@ -803,6 +808,7 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync, 
	in_out_vrr->btr.inserted_duration_in_us = 0;

	in_out_vrr->btr.frames_to_insert = 0;

	in_out_vrr->btr.frame_counter = 0;



	in_out_vrr->btr.mid_point_in_us =

				(in_out_vrr->min_duration_in_us +

				 in_out_vrr->max_duration_in_us) / 2;

drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h

+1 −0
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ struct mod_vrr_params_btr { 
	uint32_t inserted_duration_in_us;

	uint32_t frames_to_insert;

	uint32_t frame_counter;

	uint32_t margin_in_us;

};



struct mod_vrr_params_fixed_refresh {

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