[PATCH 03/13] drm/sun4i: vi scaler: Restore opaque alpha in video modes

The DE3 mixer initialization clears the entire mixer register space. This
also clears VSU_GLOBAL_ALPHA, despite its hardware reset value being 0xff.

The VI scaler uses Video Normal mode for subsampled YUV formats. In this
mode, VSU_GLOBAL_ALPHA provides the scaler output alpha. Leaving the
register at zero causes the scaler to produce fully transparent output.

Set VSU_GLOBAL_ALPHA to 0xff whenever configuring a DE3 or newer VI
scaler. The register is ignored in UI scaling mode.

Fixes: c50519e6db4d ("drm/sun4i: Add basic support for DE3")
Signed-off-by: Jernej Skrabec <[email protected]>
---
 drivers/gpu/drm/sun4i/sun8i_vi_scaler.c | 2 ++
 drivers/gpu/drm/sun4i/sun8i_vi_scaler.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun8i_vi_scaler.c b/drivers/gpu/drm/sun4i/sun8i_vi_scaler.c
index d4412a62c2f0..a5cc99981006 100644
--- a/drivers/gpu/drm/sun4i/sun8i_vi_scaler.c
+++ b/drivers/gpu/drm/sun4i/sun8i_vi_scaler.c
@@ -975,6 +975,8 @@ void sun8i_vi_scaler_setup(struct sun8i_layer *layer,
 
 		regmap_write(layer->regs,
 			     SUN50I_SCALER_VSU_SCALE_MODE(base), val);
+		regmap_write(layer->regs,
+			     SUN50I_SCALER_VSU_GLB_ALPHA(base), 0xff);
 	}
 
 	regmap_write(layer->regs,
diff --git a/drivers/gpu/drm/sun4i/sun8i_vi_scaler.h b/drivers/gpu/drm/sun4i/sun8i_vi_scaler.h
index 245fe2f431c3..d89c0cbe188d 100644
--- a/drivers/gpu/drm/sun4i/sun8i_vi_scaler.h
+++ b/drivers/gpu/drm/sun4i/sun8i_vi_scaler.h
@@ -36,6 +36,7 @@
 #define SUN50I_SCALER_VSU_EDSCL_CTRL(base)		((base) + 0x28)
 #define SUN50I_SCALER_VSU_ANGLE_THR(base)		((base) + 0x2c)
 #define SUN8I_SCALER_VSU_OUTSIZE(base)		((base) + 0x40)
+#define SUN50I_SCALER_VSU_GLB_ALPHA(base)	((base) + 0x44)
 #define SUN8I_SCALER_VSU_YINSIZE(base)		((base) + 0x80)
 #define SUN8I_SCALER_VSU_YHSTEP(base)		((base) + 0x88)
 #define SUN8I_SCALER_VSU_YVSTEP(base)		((base) + 0x8c)
-- 
2.43.0