From a4c103ac30de69d2248f073ab3f65915d12d26ed Mon Sep 17 00:00:00 2001
From: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Date: Tue, 7 Sep 2021 17:15:34 +0200
Subject: drm/stm: ltdc: add layer alpha support
Git-commit: c20351ad58c9d352cd73b4ae34ce582de424cb52
Patch-mainline: v5.16-rc1
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
Android Hardware Composer supports alpha values applied to layers.
Enabling non-opaque layers for the STM CRTC could help offload GPU
resources for screen composition.
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Acked-by: Yannick Fertre <yannick.fertre@foss.st.com>
Reviewed-by: Yannick Fertre <yannick.fertre@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210907151534.6013-1-raphael.gallais-pou@foss.st.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/stm/ltdc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index bd603ef5e935..dbdee954692a 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -845,7 +845,7 @@ static void ltdc_plane_atomic_update(struct drm_plane *plane,
LXCFBLR_CFBLL | LXCFBLR_CFBP, val);
/* Specifies the constant alpha value */
- val = CONSTA_MAX;
+ val = newstate->alpha >> 8;
reg_update_bits(ldev->regs, LTDC_L1CACR + lofs, LXCACR_CONSTA, val);
/* Specifies the blending factors */
@@ -997,6 +997,8 @@ static struct drm_plane *ltdc_plane_create(struct drm_device *ddev,
drm_plane_helper_add(plane, <dc_plane_helper_funcs);
+ drm_plane_create_alpha_property(plane);
+
DRM_DEBUG_DRIVER("plane:%d created\n", plane->base.id);
return plane;
--
2.38.1