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 <mca...@igalia.com> --- v1 -> v2: https://lore.kernel.org/dri-devel/20230428122751.24271-1-mca...@igalia.com/T/ * Rebased on top of drm-misc-next. --- drivers/gpu/drm/vkms/vkms_composer.c | 49 ++++++++++++++++++---------- drivers/gpu/drm/vkms/vkms_drv.h | 2 ++ drivers/gpu/drm/vkms/vkms_plane.c | 9 +++++ 3 files changed, 42 insertions(+), 18 deletions(-) diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c index d170a8e89b95..68a476461824 100644 --- a/drivers/gpu/drm/vkms/vkms_composer.c +++ b/drivers/gpu/drm/vkms/vkms_composer.c @@ -12,33 +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 * @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; @@ -48,9 +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); } } @@ -98,7 +112,7 @@ static void fill_background(const struct pixel_argb_u16 *background_color, * @stage_buffer: The line with the pixels from plane being blend to the output * @row_size: The size, in bytes, of a single row * - * 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. */ @@ -126,8 +140,7 @@ static void blend(struct vkms_writeback_job *wb, continue; vkms_compose_row(stage_buffer, plane[i], y_pos); - 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 d25e0aae91f2..20e2c520885e 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.h +++ b/drivers/gpu/drm/vkms/vkms_drv.h @@ -28,6 +28,8 @@ struct vkms_frame_info { struct drm_rect src, dst; struct drm_rect rotated; struct iosys_map map[DRM_FORMAT_MAX_PLANES]; + u16 alpha; + u16 pixel_blend_mode; unsigned int rotation; unsigned int offset; unsigned int pitch; diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c index e5c625ab8e3e..891aa566acda 100644 --- a/drivers/gpu/drm/vkms/vkms_plane.c +++ b/drivers/gpu/drm/vkms/vkms_plane.c @@ -113,6 +113,8 @@ static void vkms_plane_atomic_update(struct drm_plane *plane, memcpy(&frame_info->src, &new_state->src, sizeof(struct drm_rect)); memcpy(&frame_info->dst, &new_state->dst, sizeof(struct drm_rect)); memcpy(&frame_info->rotated, &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); @@ -212,6 +214,13 @@ 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)); + drm_plane_create_rotation_property(&plane->base, DRM_MODE_ROTATE_0, DRM_MODE_ROTATE_MASK | DRM_MODE_REFLECT_MASK); -- 2.41.0
