sna/gen3: Ensure that depth read/writes are disabled before first use

Our goal is to achieve "single-stream" rendering where the entire
RenderCache is allocated to the colour buffer (rather than split between
colour and depth). In theory all that is required is for the pipeline
not to reference the depth buffer at all, however it is not made clear
when that evaluation is made.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 14 insertions, 1 deletions

diff --git a/src/sna/gen3_render.c b/src/sna/gen3_render.c
index 33bdfd24..ffde637f 100644
--- a/src/sna/gen3_render.c
+++ b/src/sna/gen3_render.c
@@ -94,6 +94,12 @@ static const struct blendinfo {
 	/* Add */	{0, 0, BLENDFACT_ONE, BLENDFACT_ONE},
 };
 
+#define S6_COLOR_WRITE_ONLY \
+	(S6_COLOR_WRITE_ENABLE | \
+	 BLENDFUNC_ADD << S6_CBUF_BLEND_FUNC_SHIFT | \
+	 BLENDFACT_ONE << S6_CBUF_SRC_BLEND_FACT_SHIFT | \
+	 BLENDFACT_ZERO << S6_CBUF_DST_BLEND_FACT_SHIFT)
+
 static const struct formatinfo {
 	unsigned int fmt, xfmt;
 	uint32_t card_fmt;
@@ -140,6 +146,9 @@ static uint32_t gen3_get_blend_cntl(int op,
 	uint32_t sblend = gen3_blend_op[op].src_blend;
 	uint32_t dblend = gen3_blend_op[op].dst_blend;
 
+	if (op <= PictOpSrc) /* for clear and src disable blending */
+		return S6_COLOR_WRITE_ONLY;
+
 	/* If there's no dst alpha channel, adjust the blend op so that we'll
 	 * treat it as always 1.
 	 */
@@ -1161,13 +1170,14 @@ static void gen3_emit_invariant(struct sna *sna)
 		  CSB_TCB(6, 6) |
 		  CSB_TCB(7, 7));
 
-	OUT_BATCH(_3DSTATE_LOAD_STATE_IMMEDIATE_1 | I1_LOAD_S(3) | I1_LOAD_S(4) | I1_LOAD_S(5) | 2);
+	OUT_BATCH(_3DSTATE_LOAD_STATE_IMMEDIATE_1 | I1_LOAD_S(3) | I1_LOAD_S(4) | I1_LOAD_S(5) | I1_LOAD_S(6) | 3);
 	OUT_BATCH(0); /* Disable texture coordinate wrap-shortest */
 	OUT_BATCH((1 << S4_POINT_WIDTH_SHIFT) |
 		  S4_LINE_WIDTH_ONE |
 		  S4_CULLMODE_NONE |
 		  S4_VFMT_XY);
 	OUT_BATCH(0); /* Disable fog/stencil. *Enable* write mask. */
+	OUT_BATCH(S6_COLOR_WRITE_ONLY); /* Disable blending, depth */
 
 	OUT_BATCH(_3DSTATE_SCISSOR_ENABLE_CMD | DISABLE_SCISSOR_RECT);
 	OUT_BATCH(_3DSTATE_DEPTH_SUBRECT_DISABLE);
@@ -2191,6 +2201,8 @@ gen3_composite_set_target(struct sna *sna,
 	if (priv == NULL)
 		return FALSE;
 
+	/* XXX This should only be necessary if we fail to disable depth! */
+#if 0
 	if (priv->gpu_bo->pitch < 16) {
 		struct kgem_bo *bo;
 
@@ -2206,6 +2218,7 @@ gen3_composite_set_target(struct sna *sna,
 		kgem_bo_destroy(&sna->kgem, priv->gpu_bo);
 		priv->gpu_bo = bo;
 	}
+#endif
 
 	op->dst.bo = priv->gpu_bo;
 	op->damage = &priv->gpu_damage;