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Subject[PATCH 5.2 046/137] drm/amd/display: Fix frames_to_insert math
Date
From: Bayan Zabihiyan <bayan.zabihiyan@amd.com>

[ Upstream commit a463b263032f7c98c5912207db43be1aa34a6438 ]

[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: Bayan Zabihiyan <bayan.zabihiyan@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../amd/display/modules/freesync/freesync.c | 27 ++++++++++++-------
1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
index 19b1eaebe4840..000a9db9dad82 100644
--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -433,6 +433,12 @@ 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;
@@ -885,8 +891,8 @@ 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;
@@ -913,7 +919,7 @@ 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;

@@ -929,15 +935,15 @@ 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;
@@ -948,17 +954,18 @@ 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;
--
2.20.1


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