[PATCH] drm/sun4i: Enable output signal premultiplication for DE2/DE3

From: Roman Stratiienko
Date: Thu Jun 02 2022 - 06:11:28 EST


Otherwise alpha value is discarded, resulting incorrect pixel
apperance on the display.

This also fixes missing transparency for the most bottom layer.

Test applications and videos w/ w/o this patch are available at [1].

[1]: https://github.com/GloDroid/glodroid_tests/issues/1
Signed-off-by: Roman Stratiienko <r.stratiienko@xxxxxxxxx>
---
drivers/gpu/drm/sun4i/sun8i_mixer.c | 2 ++
drivers/gpu/drm/sun4i/sun8i_mixer.h | 1 +
2 files changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c b/drivers/gpu/drm/sun4i/sun8i_mixer.c
index 6b1711a9a71f..71ab0a00b4de 100644
--- a/drivers/gpu/drm/sun4i/sun8i_mixer.c
+++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c
@@ -320,6 +320,8 @@ static void sun8i_mixer_mode_set(struct sunxi_engine *engine,
else
val = 0;

+ val |= SUN8I_MIXER_BLEND_OUTCTL_PREMULTIPLY;
+
regmap_update_bits(engine->regs, SUN8I_MIXER_BLEND_OUTCTL(bld_base),
SUN8I_MIXER_BLEND_OUTCTL_INTERLACED, val);

diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.h b/drivers/gpu/drm/sun4i/sun8i_mixer.h
index ebfc276b2464..bc12c95af6f3 100644
--- a/drivers/gpu/drm/sun4i/sun8i_mixer.h
+++ b/drivers/gpu/drm/sun4i/sun8i_mixer.h
@@ -65,6 +65,7 @@
#define SUN8I_MIXER_BLEND_ROUTE_PIPE_MSK(n) (0xf << ((n) << 2))
#define SUN8I_MIXER_BLEND_ROUTE_PIPE_SHIFT(n) ((n) << 2)

+#define SUN8I_MIXER_BLEND_OUTCTL_PREMULTIPLY BIT(0)
#define SUN8I_MIXER_BLEND_OUTCTL_INTERLACED BIT(1)

#define SUN50I_MIXER_BLEND_CSC_CTL_EN(ch) BIT(ch)
--
2.30.2