From: Harry Wentland <harry.wentland@amd.com>
Date: Wed, 29 Nov 2017 10:16:51 -0500
Subject: drm/amd/display: Use macro for isnan check
Git-commit: 3f4e3a282e1235a9ab46d063b0902c00b6afc6a9
Patch-mainline: v4.16-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

In code provided by HW teams we do a NaN check on floats
by comparing the number against itself. This confuses most
people including myself. Macro it out to make it self-explanatory.

Don't do a NaN check for int.

v2: parantheses around 'number' expression

Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c |   18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c
+++ b/drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c
@@ -25,37 +25,35 @@
 
 #include "dcn_calc_math.h"
 
+#define isNaN(number) ((number) != (number))
+
 float dcn_bw_mod(const float arg1, const float arg2)
 {
-	if (arg1 != arg1)
+	if (isNaN(arg1))
 		return arg2;
-	if (arg2 != arg2)
+	if (isNaN(arg2))
 		return arg1;
 	return arg1 - arg1 * ((int) (arg1 / arg2));
 }
 
 float dcn_bw_min2(const float arg1, const float arg2)
 {
-	if (arg1 != arg1)
+	if (isNaN(arg1))
 		return arg2;
-	if (arg2 != arg2)
+	if (isNaN(arg2))
 		return arg1;
 	return arg1 < arg2 ? arg1 : arg2;
 }
 
 unsigned int dcn_bw_max(const unsigned int arg1, const unsigned int arg2)
 {
-	if (arg1 != arg1)
-		return arg2;
-	if (arg2 != arg2)
-		return arg1;
 	return arg1 > arg2 ? arg1 : arg2;
 }
 float dcn_bw_max2(const float arg1, const float arg2)
 {
-	if (arg1 != arg1)
+	if (isNaN(arg1))
 		return arg2;
-	if (arg2 != arg2)
+	if (isNaN(arg2))
 		return arg1;
 	return arg1 > arg2 ? arg1 : arg2;
 }