Re: [PATCH v2] drm/vc4: Add support for plane alpha

2018-04-23 Thread Eric Anholt 
Stefan Schake  writes:

> The HVS supports mixing fixed alpha with per-pixel alpha or
> setting a fixed plane alpha in case there is no per-pixel information.
> This allows us to support the generic DRM plane alpha property.
>
> Signed-off-by: Stefan Schake 

Applied to drm-misc-next.  Thanks!

> @@ -565,6 +567,13 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
> SCALER_POS1_SCL_HEIGHT));
>   }
>  
> + /* Don't waste cycles mixing with plane alpha if the set alpha
> +  * is opaque or there is no per-pixel alpha information.
> +  * In any case we use the alpha property value as the fixed alpha.
> +  */
> + mix_plane_alpha = state->alpha != DRM_BLEND_ALPHA_OPAQUE &&
> +   fb->format->has_alpha;
> +
>   /* Position Word 2: Source Image Size, Alpha */
>   vc4_state->pos2_offset = vc4_state->dlist_count;
>   vc4_dlist_write(vc4_state,
> @@ -572,6 +581,7 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
> SCALER_POS2_ALPHA_MODE_PIPELINE :
> SCALER_POS2_ALPHA_MODE_FIXED,
> SCALER_POS2_ALPHA_MODE) |
> + (mix_plane_alpha ? SCALER_POS2_ALPHA_MIX : 0) |
>   (fb->format->has_alpha ? SCALER_POS2_ALPHA_PREMULT : 0) 
> |
>   VC4_SET_FIELD(vc4_state->src_w[0], SCALER_POS2_WIDTH) |
>   VC4_SET_FIELD(vc4_state->src_h[0], SCALER_POS2_HEIGHT));

In an interesting note from the docs, if you'd set SCALER_POS2_ALPHA_MIX
with SCALER_POS2_ALPHA_MODE_FIXED, you'd get the fixed alpha squared!


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[PATCH v2] drm/vc4: Add support for plane alpha

2018-04-20 Thread Stefan Schake 
The HVS supports mixing fixed alpha with per-pixel alpha or
setting a fixed plane alpha in case there is no per-pixel information.
This allows us to support the generic DRM plane alpha property.

Signed-off-by: Stefan Schake 
---
v2: Non-opaque plane alpha can trigger the background blending issue
and we need to hint the CRTC that background fill might be required.

 drivers/gpu/drm/vc4/vc4_plane.c | 21 +
 drivers/gpu/drm/vc4/vc4_regs.h  |  1 +
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
index c3a37a99e601..3483c05cc3d6 100644
--- a/drivers/gpu/drm/vc4/vc4_plane.c
+++ b/drivers/gpu/drm/vc4/vc4_plane.c
@@ -201,6 +201,7 @@ static void vc4_plane_reset(struct drm_plane *plane)
return;
 
plane->state = _state->base;
+   plane->state->alpha = DRM_BLEND_ALPHA_OPAQUE;
vc4_state->base.plane = plane;
 }
 
@@ -467,6 +468,7 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
u32 ctl0_offset = vc4_state->dlist_count;
const struct hvs_format *format = 
vc4_get_hvs_format(fb->format->format);
int num_planes = drm_format_num_planes(format->drm);
+   bool mix_plane_alpha;
bool covers_screen;
u32 scl0, scl1, pitch0;
u32 lbm_size, tiling;
@@ -552,7 +554,7 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
/* Position Word 0: Image Positions and Alpha Value */
vc4_state->pos0_offset = vc4_state->dlist_count;
vc4_dlist_write(vc4_state,
-   VC4_SET_FIELD(0xff, SCALER_POS0_FIXED_ALPHA) |
+   VC4_SET_FIELD(state->alpha >> 8, 
SCALER_POS0_FIXED_ALPHA) |
VC4_SET_FIELD(vc4_state->crtc_x, SCALER_POS0_START_X) |
VC4_SET_FIELD(vc4_state->crtc_y, SCALER_POS0_START_Y));
 
@@ -565,6 +567,13 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
  SCALER_POS1_SCL_HEIGHT));
}
 
+   /* Don't waste cycles mixing with plane alpha if the set alpha
+* is opaque or there is no per-pixel alpha information.
+* In any case we use the alpha property value as the fixed alpha.
+*/
+   mix_plane_alpha = state->alpha != DRM_BLEND_ALPHA_OPAQUE &&
+ fb->format->has_alpha;
+
/* Position Word 2: Source Image Size, Alpha */
vc4_state->pos2_offset = vc4_state->dlist_count;
vc4_dlist_write(vc4_state,
@@ -572,6 +581,7 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
  SCALER_POS2_ALPHA_MODE_PIPELINE :
  SCALER_POS2_ALPHA_MODE_FIXED,
  SCALER_POS2_ALPHA_MODE) |
+   (mix_plane_alpha ? SCALER_POS2_ALPHA_MIX : 0) |
(fb->format->has_alpha ? SCALER_POS2_ALPHA_PREMULT : 0) 
|
VC4_SET_FIELD(vc4_state->src_w[0], SCALER_POS2_WIDTH) |
VC4_SET_FIELD(vc4_state->src_h[0], SCALER_POS2_HEIGHT));
@@ -653,10 +663,11 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
vc4_state->crtc_w == state->crtc->mode.hdisplay &&
vc4_state->crtc_h == state->crtc->mode.vdisplay;
/* Background fill might be necessary when the plane has per-pixel
-* alpha content and blends from the background or does not cover
-* the entire screen.
+* alpha content or a non-opaque plane alpha and could blend from the
+* background or does not cover the entire screen.
 */
-   vc4_state->needs_bg_fill = fb->format->has_alpha || !covers_screen;
+   vc4_state->needs_bg_fill = fb->format->has_alpha || !covers_screen ||
+  state->alpha != DRM_BLEND_ALPHA_OPAQUE;
 
return 0;
 }
@@ -916,5 +927,7 @@ struct drm_plane *vc4_plane_init(struct drm_device *dev,
 
drm_plane_helper_add(plane, _plane_helper_funcs);
 
+   drm_plane_create_alpha_property(plane);
+
return plane;
 }
diff --git a/drivers/gpu/drm/vc4/vc4_regs.h b/drivers/gpu/drm/vc4/vc4_regs.h
index 4af3e29d076a..d1fb6fec46eb 100644
--- a/drivers/gpu/drm/vc4/vc4_regs.h
+++ b/drivers/gpu/drm/vc4/vc4_regs.h
@@ -945,6 +945,7 @@ enum hvs_pixel_format {
 #define SCALER_POS2_ALPHA_MODE_FIXED_NONZERO   2
 #define SCALER_POS2_ALPHA_MODE_FIXED_OVER_0x07 3
 #define SCALER_POS2_ALPHA_PREMULT  BIT(29)
+#define SCALER_POS2_ALPHA_MIX  BIT(28)
 
 #define SCALER_POS2_HEIGHT_MASKVC4_MASK(27, 16)
 #define SCALER_POS2_HEIGHT_SHIFT   16
-- 
2.14.1

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