[Mesa-dev] [PATCH] gallium/u_blitter: don't use TXF for scaled blits

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

There seems to be a rounding difference with F2I vs nearest filtering.
The precise problem in the rounding is unknown.

This fixes an incorrect output with OpenMAX encoding.
---
 src/gallium/auxiliary/util/u_blitter.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/gallium/auxiliary/util/u_blitter.c b/src/gallium/auxiliary/util/u_blitter.c
index c38534d..65c6f5d 100644
--- a/src/gallium/auxiliary/util/u_blitter.c
+++ b/src/gallium/auxiliary/util/u_blitter.c
@@ -1770,29 +1770,31 @@ void util_blitter_blit_generic(struct blitter_context *blitter,
 
    blit_color = has_color && (mask & PIPE_MASK_RGBA);
    blit_depth = has_depth && (mask & PIPE_MASK_Z);
    blit_stencil = has_stencil && (mask & PIPE_MASK_S) &&
                   ctx->has_stencil_export;
 
    if (!blit_stencil && !blit_depth && !blit_color) {
       return;
    }
 
-   if (blit_stencil ||
-       (dstbox->width == abs(srcbox->width) &&
-        dstbox->height == abs(srcbox->height))) {
+   bool is_scaled = dstbox->width != abs(srcbox->width) ||
+                    dstbox->height != abs(srcbox->height);
+
+   if (blit_stencil || !is_scaled)
       filter = PIPE_TEX_FILTER_NEAREST;
-   }
 
    bool use_txf = false;
 
+   /* Don't support scaled blits. The TXF shader uses F2I for rounding. */
    if (ctx->has_txf &&
+       !is_scaled &&
        filter == PIPE_TEX_FILTER_NEAREST &&
        src->target != PIPE_TEXTURE_CUBE &&
        src->target != PIPE_TEXTURE_CUBE_ARRAY) {
       int src_width = u_minify(src_width0, src->u.tex.first_level);
       int src_height = u_minify(src_height0, src->u.tex.first_level);
       int src_depth = src->u.tex.last_layer + 1;
       struct pipe_box box = *srcbox;
 
       /* Eliminate negative width/height/depth. */
       if (box.width < 0) {
-- 
2.7.4