Following the DRM assumption, VKMS currently assumes that the alpha is
pre-multiplied. Moreover, it doesn't support the alpha property.
So, first, implement the alpha property to VKMS and then, the blend
mode property. In order to support all possible supported modes,
change the pre_mul_blend_channel() function to check the plane blend
mode and apply the correct blend formula, following the DRM
convention, using the proper plane alpha value.
Tested with igt@kms_plane_alpha_blend.
Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx>
---
drivers/gpu/drm/vkms/vkms_composer.c | 50 ++++++++++++++++++----------
drivers/gpu/drm/vkms/vkms_drv.h | 2 ++
drivers/gpu/drm/vkms/vkms_plane.c | 10 ++++++
3 files changed, 44 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index 80164e79af00..bc80ea2a1ab0 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -4,6 +4,7 @@
#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
+#include <drm/drm_blend.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_vblank.h>
@@ -11,33 +12,47 @@
#include "vkms_drv.h"
-static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha)
+static u16 blend_channel(struct vkms_frame_info *frame_info, u16 src, u16 dst, u16 alpha)
{
u32 new_color;
- new_color = (src * 0xffff + dst * (0xffff - alpha));
+ switch (frame_info->pixel_blend_mode) {
+ case DRM_MODE_BLEND_PIXEL_NONE:
+ new_color = 0xffff * frame_info->alpha * src
+ + (0xfffe0001 - 0xffff * frame_info->alpha) * dst;
+ break;
+ case DRM_MODE_BLEND_COVERAGE:
+ new_color = alpha * frame_info->alpha * src
+ + (0xfffe0001 - alpha * frame_info->alpha) * dst;
+ break;
+ case DRM_MODE_BLEND_PREMULTI:
+ default:
+ new_color = 0xffff * frame_info->alpha * src
+ + (0xfffe0001 - alpha * frame_info->alpha) * dst;
+ break;
+ }
- return DIV_ROUND_CLOSEST(new_color, 0xffff);
+ return DIV_ROUND_CLOSEST(new_color, 0xfffe0001);
}
/**
- * pre_mul_alpha_blend - alpha blending equation
+ * alpha_blend - alpha blending equation
* @src_frame_info: source framebuffer's metadata
* @stage_buffer: The line with the pixels from src_plane
* @output_buffer: A line buffer that receives all the blends output
*
* Using the information from the `frame_info`, this blends only the
* necessary pixels from the `stage_buffer` to the `output_buffer`
- * using premultiplied blend formula.
+ * using the adequate blend formula depending on the plane blend mode
+ * (see blend_channel()).
*
- * The current DRM assumption is that pixel color values have been already
- * pre-multiplied with the alpha channel values. See more
- * drm_plane_create_blend_mode_property(). Also, this formula assumes a
- * completely opaque background.
+ * By default, the current DRM assumption is that pixel color values have
+ * been already pre-multiplied with the alpha channel values. See more
+ * drm_plane_create_blend_mode_property().
*/
-static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info,
- struct line_buffer *stage_buffer,
- struct line_buffer *output_buffer)
+static void alpha_blend(struct vkms_frame_info *frame_info,
+ struct line_buffer *stage_buffer,
+ struct line_buffer *output_buffer)
{
int x_dst = frame_info->dst.x1;
struct pixel_argb_u16 *out = output_buffer->pixels + x_dst;
@@ -47,9 +62,9 @@ static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info,
for (int x = 0; x < x_limit; x++) {
out[x].a = (u16)0xffff;
- out[x].r = pre_mul_blend_channel(in[x].r, out[x].r, in[x].a);
- out[x].g = pre_mul_blend_channel(in[x].g, out[x].g, in[x].a);
- out[x].b = pre_mul_blend_channel(in[x].b, out[x].b, in[x].a);
+ out[x].r = blend_channel(frame_info, in[x].r, out[x].r, in[x].a);
+ out[x].g = blend_channel(frame_info, in[x].g, out[x].g, in[x].a);
+ out[x].b = blend_channel(frame_info, in[x].b, out[x].b, in[x].a);
}
}
@@ -75,7 +90,7 @@ static void fill_background(const struct pixel_argb_u16 *background_color,
* @output_buffer: A buffer of a row that will receive the result of the blend(s)
* @stage_buffer: The line with the pixels from plane being blend to the output
*
- * This function blends the pixels (Using the `pre_mul_alpha_blend`)
+ * This function blends the pixels (Using the `alpha_blend()`)
* from all planes, calculates the crc32 of the output from the former step,
* and, if necessary, convert and store the output to the writeback buffer.
*/
@@ -100,8 +115,7 @@ static void blend(struct vkms_writeback_job *wb,
continue;
vkms_compose_row(stage_buffer, plane[i], y);
- pre_mul_alpha_blend(plane[i]->frame_info, stage_buffer,
- output_buffer);
+ alpha_blend(plane[i]->frame_info, stage_buffer, output_buffer);
}
*crc32 = crc32_le(*crc32, (void *)output_buffer->pixels, row_size);
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index f152d54baf76..e646a153831b 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -27,6 +27,8 @@ struct vkms_frame_info {
struct drm_framebuffer *fb;
struct drm_rect src, dst;
struct iosys_map map[DRM_FORMAT_MAX_PLANES];
+ u16 alpha;
+ u16 pixel_blend_mode;
unsigned int offset;
unsigned int pitch;
unsigned int cpp;
diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
index 87b2bccaf083..fd57ff8cb20f 100644
--- a/drivers/gpu/drm/vkms/vkms_plane.c
+++ b/drivers/gpu/drm/vkms/vkms_plane.c
@@ -4,6 +4,7 @@
#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
+#include <drm/drm_blend.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
@@ -111,6 +112,8 @@ static void vkms_plane_atomic_update(struct drm_plane *plane,
frame_info = vkms_plane_state->frame_info;
memcpy(&frame_info->src, &new_state->src, sizeof(struct drm_rect));
memcpy(&frame_info->dst, &new_state->dst, sizeof(struct drm_rect));
+ frame_info->alpha = new_state->alpha;
+ frame_info->pixel_blend_mode = new_state->pixel_blend_mode;
frame_info->fb = fb;
memcpy(&frame_info->map, &shadow_plane_state->data, sizeof(frame_info->map));
drm_framebuffer_get(frame_info->fb);
@@ -201,5 +204,12 @@ struct vkms_plane *vkms_plane_init(struct vkms_device *vkmsdev,
drm_plane_helper_add(&plane->base, &vkms_plane_helper_funcs);
+ drm_plane_create_alpha_property(&plane->base);
+
+ drm_plane_create_blend_mode_property(&plane->base,
+ BIT(DRM_MODE_BLEND_PIXEL_NONE) |
+ BIT(DRM_MODE_BLEND_PREMULTI) |
+ BIT(DRM_MODE_BLEND_COVERAGE));
+
return plane;
}
--
2.40.0
