From: Dave Airlie <airlied@redhat.com>
Date: Tue, 3 Oct 2017 13:49:42 +1000
Subject: amdgpu/dc: use kernel ilog2 for log_2.
Git-commit: 23d433fabef852e82053186b60710d138f727284
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

This should produce the same result.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/display/dc/basics/conversion.c |   10 ----------
 drivers/gpu/drm/amd/display/dc/basics/conversion.h |    5 ++++-
 2 files changed, 4 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/basics/conversion.c
+++ b/drivers/gpu/drm/amd/display/dc/basics/conversion.c
@@ -102,13 +102,3 @@ void convert_float_matrix(
 		matrix[i] = (uint16_t)reg_value;
 	}
 }
-
-unsigned int log_2(unsigned int num)
-{
-	unsigned int result = 0;
-
-	while ((num >>= 1) != 0)
-		result++;
-
-	return result;
-}
--- a/drivers/gpu/drm/amd/display/dc/basics/conversion.h
+++ b/drivers/gpu/drm/amd/display/dc/basics/conversion.h
@@ -38,6 +38,9 @@ void convert_float_matrix(
 	struct fixed31_32 *flt,
 	uint32_t buffer_size);
 
-unsigned int log_2(unsigned int num);
+static inline unsigned int log_2(unsigned int num)
+{
+	return ilog2(num);
+}
 
 #endif