drm/stm: ltdc: reset plane transparency after plane disable

[ Upstream commit 02fa62d41c8abff945bae5bfc3ddcf4721496aca ]

The plane's opacity should be reseted while the plane
is disabled. It prevents from seeing a possible global
or layer background color set earlier.

Signed-off-by: Yannick Fertre <yannick.fertre@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240712131344.98113-1-yannick.fertre@foss.st.com
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 056642d12265cf1c8bf98da3a7f71d23c5db6725..0832b749b66e7fe3648e118215f92cce6b8947e8 100644 (file)
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -1513,6 +1513,9 @@ static void ltdc_plane_atomic_disable(struct drm_plane *plane,
        /* Disable layer */
        regmap_write_bits(ldev->regmap, LTDC_L1CR + lofs, LXCR_LEN | LXCR_CLUTEN |  LXCR_HMEN, 0);
 
+       /* Reset the layer transparency to hide any related background color */
+       regmap_write_bits(ldev->regmap, LTDC_L1CACR + lofs, LXCACR_CONSTA, 0x00);
+
        /* Commit shadow registers = update plane at next vblank */
        if (ldev->caps.plane_reg_shadow)
                regmap_write_bits(ldev->regmap, LTDC_L1RCR + lofs,