The pre_mul_alpha_blend is dedicated to blending, so to avoid mixing
different concepts (coordinate calculation and color management), extract
the x_limit and x_dst computation outside of this helper.
It also increases the maintainability by grouping the computation related
to coordinates in the same place: the loop in `blend`.
Signed-off-by: Louis Chauvet <louis.chau...@bootlin.com>
---
drivers/gpu/drm/vkms/vkms_composer.c | 40 +++++++++++++++++-------------------
1 file changed, 19 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c
b/drivers/gpu/drm/vkms/vkms_composer.c
index da0651a94c9b..45b111c74884 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -24,34 +24,30 @@ static u16 pre_mul_blend_channel(u16 src, u16 dst, u16
alpha)
/**
* pre_mul_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
+ * @x_start: The start offset
+ * @pixel_count: The number of pixels to blend
*
- * 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.
+ * The pixels 0..@pixel_count in stage_buffer are blended at
@x_start..@x_start+@pixel_count in
+ * output_buffer.
*
* 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.
*/
-static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info,
- struct line_buffer *stage_buffer,
- struct line_buffer *output_buffer)
+static void pre_mul_alpha_blend(const struct line_buffer *stage_buffer,
+ struct line_buffer *output_buffer, int x_start,
int pixel_count)
{
- int x_dst = frame_info->dst.x1;
- struct pixel_argb_u16 *out = output_buffer->pixels + x_dst;
- struct pixel_argb_u16 *in = stage_buffer->pixels;
- int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst),
- stage_buffer->n_pixels);
-
- 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);
+ struct pixel_argb_u16 *out = &output_buffer->pixels[x_start];
+ const struct pixel_argb_u16 *in = stage_buffer->pixels;
+
+ for (int i = 0; i < pixel_count; i++) {
+ out[i].a = (u16)0xffff;
+ out[i].r = pre_mul_blend_channel(in[i].r, out[i].r, in[i].a);
+ out[i].g = pre_mul_blend_channel(in[i].g, out[i].g, in[i].a);
+ out[i].b = pre_mul_blend_channel(in[i].b, out[i].b, in[i].a);
}
}
@@ -183,7 +179,7 @@ static void blend(struct vkms_writeback_job *wb,
{
struct vkms_plane_state **plane = crtc_state->active_planes;
u32 n_active_planes = crtc_state->num_active_planes;
- int y_pos;
+ int y_pos, x_dst, pixel_count;
const struct pixel_argb_u16 background_color = { .a = 0xffff };
@@ -201,14 +197,16 @@ static void blend(struct vkms_writeback_job *wb,
/* The active planes are composed associatively in z-order. */
for (size_t i = 0; i < n_active_planes; i++) {
+ x_dst = plane[i]->frame_info->dst.x1;
+ pixel_count = min_t(int,
drm_rect_width(&plane[i]->frame_info->dst),
+ (int)stage_buffer->n_pixels);
y_pos = get_y_pos(plane[i]->frame_info, y);
if (!check_limit(plane[i]->frame_info, y_pos))
continue;
vkms_compose_row(stage_buffer, plane[i], y_pos);
- pre_mul_alpha_blend(plane[i]->frame_info, stage_buffer,
- output_buffer);
+ pre_mul_alpha_blend(stage_buffer, output_buffer, x_dst,
pixel_count);
}
apply_lut(crtc_state, output_buffer);
--
2.43.0
