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Commit 617a89ff authored by Hamza Mahfooz's avatar Hamza Mahfooz Committed by Greg Kroah-Hartman
Browse files

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@vger.kernel.org
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2637


Fixes: a463b263 ("drm/amd/display: Fix frames_to_insert math")
Fixes: ded6119e825a ("drm/amd/display: Reinstate LFC optimization")
Reviewed-by: default avatarAurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: default avatarHamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 07b63a3d

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

+6 −3
Original line number Diff line number Diff line
@@ -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.
@@ -370,7 +372,8 @@ 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 <

		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;