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Commit a463b263 authored by Bayan Zabihiyan's avatar Bayan Zabihiyan Committed by Alex Deucher
Browse files

drm/amd/display: Fix frames_to_insert math 



[Why]
The math on deciding on how many
"frames to insert" sometimes sent us over the max refresh rate.
Also integer overflow can occur if we have high refresh rates.

[How]
Instead of clipping the  frame duration such that it doesn’t go below the min,
just remove a frame from the number of frames to insert. +
Use unsigned long long for intermediate calculations to prevent
integer overflow.

Signed-off-by: default avatarBayan Zabihiyan <bayan.zabihiyan@amd.com>
Reviewed-by: default avatarAric Cyr <Aric.Cyr@amd.com>
Acked-by: default avatarLeo Li <sunpeng.li@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 1cbcfc97

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

+17 −10
Original line number Diff line number Diff line
@@ -435,6 +435,12 @@ static void apply_below_the_range(struct core_freesync *core_freesync, 
		/* Either we've calculated the number of frames to insert,

		 * or we need to insert min duration frames

		 */

		if (last_render_time_in_us / frames_to_insert <

				in_out_vrr->min_duration_in_us){

			frames_to_insert -= (frames_to_insert > 1) ?

					1 : 0;

		}



		if (frames_to_insert > 0)

			inserted_frame_duration_in_us = last_render_time_in_us /

							frames_to_insert;
@@ -887,8 +893,8 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync, 
	struct core_freesync *core_freesync = NULL;

	unsigned long long nominal_field_rate_in_uhz = 0;

	unsigned int refresh_range = 0;

	unsigned int min_refresh_in_uhz = 0;

	unsigned int max_refresh_in_uhz = 0;

	unsigned long long min_refresh_in_uhz = 0;

	unsigned long long max_refresh_in_uhz = 0;



	if (mod_freesync == NULL)

		return;
@@ -915,7 +921,7 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync, 
		min_refresh_in_uhz = nominal_field_rate_in_uhz;



	if (!vrr_settings_require_update(core_freesync,

			in_config, min_refresh_in_uhz, max_refresh_in_uhz,

			in_config, (unsigned int)min_refresh_in_uhz, (unsigned int)max_refresh_in_uhz,

			in_out_vrr))

		return;
@@ -931,15 +937,15 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync, 
		return;



	} else {

		in_out_vrr->min_refresh_in_uhz = min_refresh_in_uhz;

		in_out_vrr->min_refresh_in_uhz = (unsigned int)min_refresh_in_uhz;

		in_out_vrr->max_duration_in_us =

				calc_duration_in_us_from_refresh_in_uhz(

						min_refresh_in_uhz);

						(unsigned int)min_refresh_in_uhz);



		in_out_vrr->max_refresh_in_uhz = max_refresh_in_uhz;

		in_out_vrr->max_refresh_in_uhz = (unsigned int)max_refresh_in_uhz;

		in_out_vrr->min_duration_in_us =

				calc_duration_in_us_from_refresh_in_uhz(

						max_refresh_in_uhz);

						(unsigned int)max_refresh_in_uhz);



		refresh_range = in_out_vrr->max_refresh_in_uhz -

				in_out_vrr->min_refresh_in_uhz;
@@ -950,17 +956,18 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync, 
	in_out_vrr->fixed.ramping_active = in_config->ramping;



	in_out_vrr->btr.btr_enabled = in_config->btr;



	if (in_out_vrr->max_refresh_in_uhz <

			2 * in_out_vrr->min_refresh_in_uhz)

		in_out_vrr->btr.btr_enabled = false;



	in_out_vrr->btr.btr_active = false;

	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 -

				in_out_vrr->min_duration_in_us) / 2;

				(in_out_vrr->min_duration_in_us +

				 in_out_vrr->max_duration_in_us) / 2;



	if (in_out_vrr->state == VRR_STATE_UNSUPPORTED) {

		in_out_vrr->adjust.v_total_min = stream->timing.v_total;