From 07e388aab042774f284a2ad75a70a194517cdad4 Mon Sep 17 00:00:00 2001
From: Hamza Mahfooz <hamza.mahfooz@amd.com>
Date: Tue, 5 Sep 2023 13:27:22 -0400
Subject: [PATCH] drm/amd/display: prevent potential division by zero errors
Git-commit: 07e388aab042774f284a2ad75a70a194517cdad4
Patch-mainline: v6.6-rc1
References: git-fixes
Alt-commit: 084f658ece139645d203fa09c77c7f96cb849bb7
There are two places in apply_below_the_range() where it's possible for
a divide by zero error to occur. So, to fix this make sure the divisor
is non-zero before attempting the computation in both cases.
Cc: stable@vger.kernel.org
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2637
Fixes: a463b263032f ("drm/amd/display: Fix frames_to_insert math")
Fixes: ded6119e825a ("drm/amd/display: Reinstate LFC optimization")
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/amd/display/modules/freesync/freesync.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
index dbd60811f95d..ef3a67409021 100644
--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -338,7 +338,9 @@ static void apply_below_the_range(struct core_freesync *core_freesync,
* - Delta for CEIL: delta_from_mid_point_in_us_1
* - Delta for FLOOR: delta_from_mid_point_in_us_2
*/
- if ((last_render_time_in_us / mid_point_frames_ceil) < in_out_vrr->min_duration_in_us) {
+ if (mid_point_frames_ceil &&
+ (last_render_time_in_us / mid_point_frames_ceil) <
+ in_out_vrr->min_duration_in_us) {
/* Check for out of range.
* If using CEIL produces a value that is out of range,
* then we are forced to use FLOOR.
@@ -385,8 +387,9 @@ 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){
+ if (frames_to_insert &&
+ (last_render_time_in_us / frames_to_insert) <
+ in_out_vrr->min_duration_in_us){
frames_to_insert -= (frames_to_insert > 1) ?
1 : 0;
}
--
2.35.3