From c66ed637f76cc1f3b585b435d06e6b409459438c Mon Sep 17 00:00:00 2001
From: Melissa Wen <mwen@igalia.com>
Date: Thu, 3 Nov 2022 17:45:00 -0100
Subject: drm/amd/display: don't enable DRM CRTC degamma property for DCE
Git-commit: 0e444a4de6b38c4593a07e4cfb5bf54c40cc79b6
Patch-mainline: v6.1-rc6
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849

DM maps DRM CRTC degamma to DPP (pre-blending) degamma block, but DCE doesn't
support programmable degamma curve anywhere. Currently, a custom degamma is
accepted by DM but just ignored by DCE driver and degamma correction isn't
actually applied. There is no way to map custom degamma in DCE, therefore, DRM
CRTC degamma property shouldn't be enabled for DCE drivers.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
index 594fe8a4d02b..64dd02970292 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
@@ -412,7 +412,7 @@ int amdgpu_dm_crtc_init(struct amdgpu_display_manager *dm,
 {
 	struct amdgpu_crtc *acrtc = NULL;
 	struct drm_plane *cursor_plane;
-
+	bool is_dcn;
 	int res = -ENOMEM;
 
 	cursor_plane = kzalloc(sizeof(*cursor_plane), GFP_KERNEL);
@@ -450,8 +450,14 @@ int amdgpu_dm_crtc_init(struct amdgpu_display_manager *dm,
 	acrtc->otg_inst = -1;
 
 	dm->adev->mode_info.crtcs[crtc_index] = acrtc;
-	drm_crtc_enable_color_mgmt(&acrtc->base, MAX_COLOR_LUT_ENTRIES,
+
+	/* Don't enable DRM CRTC degamma property for DCE since it doesn't
+	 * support programmable degamma anywhere.
+	 */
+	is_dcn = dm->adev->dm.dc->caps.color.dpp.dcn_arch;
+	drm_crtc_enable_color_mgmt(&acrtc->base, is_dcn ? MAX_COLOR_LUT_ENTRIES : 0,
 				   true, MAX_COLOR_LUT_ENTRIES);
+
 	drm_mode_crtc_set_gamma_size(&acrtc->base, MAX_COLOR_LEGACY_LUT_ENTRIES);
 
 	return 0;
-- 
2.38.1