Use alpha value to blend source value and destination value Instead of just overwrite with source value.

Signed-off-by: Sidong Yang realwakka@gmail.com --- drivers/gpu/drm/vkms/vkms_composer.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c index d5585695c64d..b776185e5cb5 100644 --- a/drivers/gpu/drm/vkms/vkms_composer.c +++ b/drivers/gpu/drm/vkms/vkms_composer.c @@ -75,6 +75,9 @@ static void blend(void *vaddr_dst, void *vaddr_src, int y_limit = y_src + h_dst; int x_limit = x_src + w_dst;

+ u8 *src, *dst; + u32 alpha, inv_alpha; + for (i = y_src, i_dst = y_dst; i < y_limit; ++i) { for (j = x_src, j_dst = x_dst; j < x_limit; ++j) { offset_dst = dest_composer->offset @@ -84,8 +87,14 @@ static void blend(void *vaddr_dst, void *vaddr_src, + (i * src_composer->pitch) + (j * src_composer->cpp);

- memcpy(vaddr_dst + offset_dst, - vaddr_src + offset_src, sizeof(u32)); + src = vaddr_src + offset_src; + dst = vaddr_dst + offset_dst; + alpha = src[3] + 1; + inv_alpha = 256 - src[3]; + dst[0] = (alpha * src[0] + inv_alpha * dst[0]) >> 8; + dst[1] = (alpha * src[1] + inv_alpha * dst[1]) >> 8; + dst[2] = (alpha * src[2] + inv_alpha * dst[2]) >> 8; + dst[3] = 0xff; } i_dst++; }