linux-kernel - [PATCH AUTOSEL 5.4 4/5] drm/amd/display: Limit user regamma to a valid value

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Date:   Wed, 21 Sep 2022 11:54:35 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Yao Wang1 <Yao.Wang1@....com>,
        Daniel Wheeler <daniel.wheeler@....com>,
        Krunoslav Kovac <Krunoslav.Kovac@....com>,
        Aric Cyr <Aric.Cyr@....com>,
        Pavle Kotarac <Pavle.Kotarac@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, harry.wentland@....com,
        sunpeng.li@....com, Rodrigo.Siqueira@....com,
        christian.koenig@....com, Xinhui.Pan@....com, airlied@...ux.ie,
        daniel@...ll.ch, HaoPing.Liu@....com,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.4 4/5] drm/amd/display: Limit user regamma to a valid value

From: Yao Wang1 <Yao.Wang1@....com>

[ Upstream commit 3601d620f22e37740cf73f8278eabf9f2aa19eb7 ]

[Why]
For HDR mode, we get total 512 tf_point and after switching to SDR mode
we actually get 400 tf_point and the rest of points(401~512) still use
dirty value from HDR mode. We should limit the rest of the points to max
value.

[How]
Limit the value when coordinates_x.x > 1, just like what we do in
translate_from_linear_space for other re-gamma build paths.

Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@....com>
Reviewed-by: Aric Cyr <Aric.Cyr@....com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@....com>
Signed-off-by: Yao Wang1 <Yao.Wang1@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/modules/color/color_gamma.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
index e042d8ce05b4..22d105635e33 100644
--- a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
+++ b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
@@ -1486,6 +1486,7 @@ static void interpolate_user_regamma(uint32_t hw_points_num,
 	struct fixed31_32 lut2;
 	struct fixed31_32 delta_lut;
 	struct fixed31_32 delta_index;
+	const struct fixed31_32 one = dc_fixpt_from_int(1);
 
 	i = 0;
 	/* fixed_pt library has problems handling too small values */
@@ -1514,6 +1515,9 @@ static void interpolate_user_regamma(uint32_t hw_points_num,
 			} else
 				hw_x = coordinates_x[i].x;
 
+			if (dc_fixpt_le(one, hw_x))
+				hw_x = one;
+
 			norm_x = dc_fixpt_mul(norm_factor, hw_x);
 			index = dc_fixpt_floor(norm_x);
 			if (index < 0 || index > 255)
-- 
2.35.1