This is a note to let you know that I've just added the patch titled
drm/amd/display: prevent potential division by zero errors
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amd-display-prevent-potential-division-by-zero-e.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c7d685580d9efc3e88f12cff3c2b5ac86d2580e0
Author: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
Date: Tue Sep 5 13:27:22 2023 -0400
drm/amd/display: prevent potential division by zero errors
[ Upstream commit 07e388aab042774f284a2ad75a70a194517cdad4 ]
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@xxxxxxxxxxxxxxx
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@xxxxxxx>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
index 5835b968cac5d..ed5c9edfdcc56 100644
--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -323,7 +323,9 @@ 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.
@@ -370,8 +372,9 @@ 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;
}
