etnaviv: set DITHER_MODE

This fixes a rendering glitch observed in SDL testscale test, where alpha
blending samples with value (1.0, 1.0, 1.0, 0.0) whitens the target instead
of having no effect.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>

diff --git a/src/gallium/drivers/etnaviv/etnaviv_blend.c b/src/gallium/drivers/etnaviv/etnaviv_blend.c
index 637586a..1f57499 100644 (file)
--- a/src/gallium/drivers/etnaviv/etnaviv_blend.c
+++ b/src/gallium/drivers/etnaviv/etnaviv_blend.c
@@ -90,6 +90,7 @@ etna_blend_state_create(struct pipe_context *pctx,
 
    co->PE_LOGIC_OP =
          VIVS_PE_LOGIC_OP_OP(logicop_enable ? so->logicop_func : LOGIC_OP_COPY) |
+         VIVS_PE_LOGIC_OP_DITHER_MODE(3) | /* TODO: related to dithering, sometimes 2 */
          0x000E4000 /* ??? */;
 
    co->fo_allowed = !alpha_enable && !logicop_enable;