[PATCH v2] drm/arm/malidp: Disable pixel alpha blending for colors that do not have alpha

From: Ayan Kumar Halder
Date: Tue Jan 23 2018 - 11:49:49 EST


From: Ayan Halder <ayan.halder@xxxxxxx>

Mali dp needs to disable pixel alpha blending (use layer alpha blending) to
display color formats that do not contain alpha bits per pixel

This patch depends on:

"[PATCH v2 01/19] drm/fourcc: Add a alpha field to drm_format_info"

Signed-off-by: Ayan Kumar Halder <ayan.halder@xxxxxxx>
---
Change in v2:
- Use struct drm_format_info->has_alpha (boolean) to determine if a color
format has alpha channel

drivers/gpu/drm/arm/malidp_planes.c | 27 ++++++++++++++++++++++-----
1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/arm/malidp_planes.c b/drivers/gpu/drm/arm/malidp_planes.c
index e741979..3b445d9 100644
--- a/drivers/gpu/drm/arm/malidp_planes.c
+++ b/drivers/gpu/drm/arm/malidp_planes.c
@@ -35,6 +35,9 @@
#define LAYER_COMP_MASK (0x3 << 12)
#define LAYER_COMP_PIXEL (0x3 << 12)
#define LAYER_COMP_PLANE (0x2 << 12)
+#define LAYER_ALPHA_OFFSET (16)
+#define LAYER_ALPHA_MASK (0xff)
+#define LAYER_ALPHA(x) (((x) & LAYER_ALPHA_MASK) << LAYER_ALPHA_OFFSET)
#define MALIDP_LAYER_COMPOSE 0x008
#define MALIDP_LAYER_SIZE 0x00c
#define LAYER_H_VAL(x) (((x) & 0x1fff) << 0)
@@ -268,6 +271,7 @@ static void malidp_de_plane_update(struct drm_plane *plane,
struct malidp_plane_state *ms = to_malidp_plane_state(plane->state);
u32 src_w, src_h, dest_w, dest_h, val;
int i;
+ bool format_has_alpha = plane->state->fb->format->has_alpha;

mp = to_malidp_plane(plane);

@@ -319,12 +323,25 @@ static void malidp_de_plane_update(struct drm_plane *plane,
if (plane->state->rotation & DRM_MODE_REFLECT_Y)
val |= LAYER_V_FLIP;

- /*
- * always enable pixel alpha blending until we have a way to change
- * blend modes
- */
val &= ~LAYER_COMP_MASK;
- val |= LAYER_COMP_PIXEL;
+ if (format_has_alpha) {
+
+ /*
+ * always enable pixel alpha blending until we have a way
+ * to change blend modes
+ */
+ val |= LAYER_COMP_PIXEL;
+ } else {
+
+ /*
+ * do not enable pixel alpha blending as the color channel
+ * does not have any alpha information
+ */
+ val |= LAYER_COMP_PLANE;
+
+ /* Set layer alpha coefficient to 0xff ie fully opaque */
+ val |= LAYER_ALPHA(0xff);
+ }

val &= ~LAYER_FLOWCFG(LAYER_FLOWCFG_MASK);
if (plane->state->crtc) {
--
2.7.4