radeonsi/gfx9: set optimal OVERWRITE_COMBINER_WATERMARK

src/gallium/drivers/radeonsi/si_pipe.h

@@ -617,6 +617,7 @@ struct si_framebuffer {
 	ubyte				color_is_int8;
 	ubyte				color_is_int10;
 	ubyte				dirty_cbufs;
+	ubyte				dcc_overwrite_combiner_watermark;
 	bool				dirty_zsbuf;
 	bool				any_dst_linear;
 	bool				CB_has_shader_readable_metadata;

src/gallium/drivers/radeonsi/si_state.c

@@ -113,12 +113,13 @@ static void si_emit_cb_render_state(struct si_context *sctx)
 				  blend &&
 				  blend->blend_enable_4bit & cb_target_mask &&
 				  sctx->framebuffer.nr_samples >= 2;
+		unsigned watermark = sctx->framebuffer.dcc_overwrite_combiner_watermark;
 
 		radeon_opt_set_context_reg(
 				sctx, R_028424_CB_DCC_CONTROL,
 				SI_TRACKED_CB_DCC_CONTROL,
 				S_028424_OVERWRITE_COMBINER_MRT_SHARING_DISABLE(1) |
-				S_028424_OVERWRITE_COMBINER_WATERMARK(4) |
+				S_028424_OVERWRITE_COMBINER_WATERMARK(watermark) |
 				S_028424_OVERWRITE_COMBINER_DISABLE(oc_disable));
 	}
 
@@ -2855,6 +2856,7 @@ static void si_set_framebuffer_state(struct pipe_context *ctx,
 	sctx->framebuffer.any_dst_linear = false;
 	sctx->framebuffer.CB_has_shader_readable_metadata = false;
 	sctx->framebuffer.DB_has_shader_readable_metadata = false;
+	unsigned num_bpp64_colorbufs = 0;
 
 	for (i = 0; i < state->nr_cbufs; i++) {
 		if (!state->cbufs[i])
@@ -2901,6 +2903,8 @@ static void si_set_framebuffer_state(struct pipe_context *ctx,
 
 		if (tex->surface.is_linear)
 			sctx->framebuffer.any_dst_linear = true;
+		if (tex->surface.bpe >= 8)
+			num_bpp64_colorbufs++;
 
 		if (vi_dcc_enabled(tex, surf->base.u.tex.level))
 			sctx->framebuffer.CB_has_shader_readable_metadata = true;
@@ -2916,6 +2920,14 @@ static void si_set_framebuffer_state(struct pipe_context *ctx,
 		}
 	}
 
+	/* For optimal DCC performance. */
+	if (sctx->chip_class == VI)
+		sctx->framebuffer.dcc_overwrite_combiner_watermark = 4;
+	else if (num_bpp64_colorbufs >= 5)
+		sctx->framebuffer.dcc_overwrite_combiner_watermark = 8;
+	else
+		sctx->framebuffer.dcc_overwrite_combiner_watermark = 6;
+
 	struct si_texture *zstex = NULL;
 
 	if (state->zsbuf) {