linux-kernel - [PATCH] drm/stm: ltdc: reset plane transparency after plane disable

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Message-ID: <20240712131344.98113-1-yannick.fertre@foss.st.com>
Date: Fri, 12 Jul 2024 15:13:44 +0200
From: Yannick Fertre <yannick.fertre@...s.st.com>
To: Yannick Fertre <yannick.fertre@...s.st.com>,
        Raphael Gallais-Pou
	<raphael.gallais-pou@...s.st.com>,
        Philippe Cornu
	<philippe.cornu@...s.st.com>,
        Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] drm/stm: ltdc: reset plane transparency after plane disable

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@...s.st.com>
---
 drivers/gpu/drm/stm/ltdc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 5576fdae4962..cb4f08673a64 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -1514,6 +1514,9 @@ 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,
-- 
2.34.1