From: Wenjing Liu <wenjing.liu@amd.com>
Date: Thu, 26 Mar 2026 16:00:34 +0000 (-0400)
Subject: drm/amd/display: fix math_mod() using arg1 instead of arg2
X-Git-Tag: v7.1-rc1~24^2~3^2~19
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=2b104fc31be0607c04188fadbd4a9fa5b50f3b99;p=thirdparty%2Fkernel%2Flinux.git

drm/amd/display: fix math_mod() using arg1 instead of arg2

[Why]
math_mod() multiplied by arg1 instead of arg2, returning a wrong
result for any non-trivial modulo operation.

[How]
Replace arg1 with arg2 in the subtraction term to correctly
implement fmod(arg1, arg2).

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---

diff --git a/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/src/dml2_standalone_libraries/lib_float_math.c b/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/src/dml2_standalone_libraries/lib_float_math.c
index e17b5ceba4471..dc5bc649f3ac9 100644
--- a/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/src/dml2_standalone_libraries/lib_float_math.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/src/dml2_standalone_libraries/lib_float_math.c
@@ -23,7 +23,7 @@ double math_mod(const double arg1, const double arg2)
 		return arg2;
 	if (isNaN(arg2))
 		return arg1;
-	return arg1 - arg1 * ((int)(arg1 / arg2));
+	return arg1 - arg2 * ((int)(arg1 / arg2));
 }
 
 double math_min2(const double arg1, const double arg2)