drm/meson: fix 1px pink line on GXM when scaling video overlay

[ Upstream commit 5c8cf1664f288098a971a1d1e65716a2b6a279e1 ]

Playing media with a resolution smaller than the crtc size requires the
video overlay to be scaled for output and GXM boards display a 1px pink
line on the bottom of the scaled overlay. Comparing with the downstream
vendor driver revealed VPP_DUMMY_DATA not being set [0].

Setting VPP_DUMMY_DATA prevents the 1px pink line from being seen.

[0] https://github.com/endlessm/linux-s905x/blob/master/drivers/amlogic/amports/video.c#L7869

Fixes: bbbe775ec5b5 ("drm: Add support for Amlogic Meson Graphic Controller")
Suggested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230303123312.155164-1-christianshewitt@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/meson/meson_vpp.c b/drivers/gpu/drm/meson/meson_vpp.c
index 1548376..5df1957 100644 (file)
--- a/drivers/gpu/drm/meson/meson_vpp.c
+++ b/drivers/gpu/drm/meson/meson_vpp.c
@@ -100,6 +100,8 @@ void meson_vpp_init(struct meson_drm *priv)
                               priv->io_base + _REG(VPP_DOLBY_CTRL));
                writel_relaxed(0x1020080,
                                priv->io_base + _REG(VPP_DUMMY_DATA1));
+               writel_relaxed(0x42020,
+                               priv->io_base + _REG(VPP_DUMMY_DATA));
        } else if (meson_vpu_is_compatible(priv, VPU_COMPATIBLE_G12A))
                writel_relaxed(0xf, priv->io_base + _REG(DOLBY_PATH_CTRL));