From 0afefd3e3efc93b51886838b055f91d8f2c5428b Mon Sep 17 00:00:00 2001
From: Dominik Behr <dbehr@chromium.org>
Date: Tue, 1 Apr 2014 18:31:12 -0700
Subject: [PATCH] xrandr: fix setting of linear gamma table

Current linear gamma table generation assues 256 entry, 8-bit precision
gamma table. This patch uses floating point arithmetic to create correct,
full precision gamma table for any case. Similar patch again master branch
has been submitted for consideration upstream to xorg-devel mailing list.
This patch allows us to test gamma table functionality on Samsung Exynos
based hardware which has 17 entry 8-bit precision gamma table.

BUG=chromium:353360
TEST=DISPLAY=:0.0 xrandr --output LVDS-1 --mode 1366x768 -gamma 0:0:0 on\
peach-pit with gamma functions enabled in kernel and xf86-video-armsoc

Signed-off-by: Dominik Behr <dbehr@chromium.org>
---
 xrandr.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/xrandr.c b/xrandr.c
index 10d034d..a5c3e14 100644
--- a/xrandr.c
+++ b/xrandr.c
@@ -1319,21 +1319,21 @@ set_gamma(void)
 
 	for (i = 0; i < size; i++) {
 	    if (output->gamma.red == 1.0 && output->brightness == 1.0)
-		gamma->red[i] = (i << 8) + i;
+		gamma->red[i] = (double)i / (double)(size - 1) * 65535.0;
 	    else
 		gamma->red[i] = dmin(pow((double)i/(double)(size - 1),
 					 output->gamma.red) * output->brightness,
 				     1.0) * 65535.0;
 
 	    if (output->gamma.green == 1.0 && output->brightness == 1.0)
-		gamma->green[i] = (i << 8) + i;
+		gamma->green[i] = (double)i / (double)(size - 1) * 65535.0;
 	    else
 		gamma->green[i] = dmin(pow((double)i/(double)(size - 1),
 					   output->gamma.green) * output->brightness,
 				       1.0) * 65535.0;
 
 	    if (output->gamma.blue == 1.0 && output->brightness == 1.0)
-		gamma->blue[i] = (i << 8) + i;
+		gamma->blue[i] = (double)i / (double)(size - 1) * 65535.0;
 	    else
 		gamma->blue[i] = dmin(pow((double)i/(double)(size - 1),
 					  output->gamma.blue) * output->brightness,
-- 
1.9.1.423.g4596e3a