radeonsi: clarify the conditions when FLUSH_AND_INV_DB is needed

FLUSH_AND_INV_DB should be done when we're changing surface state
registers of a bound depth target.

When depth_clear_value changes, si_state will modify
S_028038_ZRANGE_PRECISION so we need to flush the DB caches.

Verified with the captures from bugs cited below.

Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/1283
Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/1330
Reviewed-by: Marek Olšák <[email protected]>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4263>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4263>

1 files changed, 7 insertions, 13 deletions

diff --git a/src/gallium/drivers/radeonsi/si_clear.c b/src/gallium/drivers/radeonsi/si_clear.c
index ef48b94a46d..2af778b41ad 100644
--- a/src/gallium/drivers/radeonsi/si_clear.c
+++ b/src/gallium/drivers/radeonsi/si_clear.c
@@ -575,6 +575,7 @@ static void si_clear(struct pipe_context *ctx, unsigned buffers,
 	struct pipe_surface *zsbuf = fb->zsbuf;
 	struct si_texture *zstex =
 		zsbuf ? (struct si_texture*)zsbuf->texture : NULL;
+	bool needs_db_flush = false;
 
 	if (buffers & PIPE_CLEAR_COLOR) {
 		si_do_fast_color_clear(sctx, &buffers, color);
@@ -610,6 +611,11 @@ static void si_clear(struct pipe_context *ctx, unsigned buffers,
 			}
 
 			if (zstex->depth_clear_value != (float)depth) {
+				if ((zstex->depth_clear_value != 0) != (depth != 0)) {
+					/* ZRANGE_PRECISION register of a bound surface will change so we
+					 * must flush the DB caches. */
+					needs_db_flush = true;
+				}
 				/* Update DB_DEPTH_CLEAR. */
 				zstex->depth_clear_value = depth;
 				sctx->framebuffer.dirty_zsbuf = true;
@@ -641,19 +647,7 @@ static void si_clear(struct pipe_context *ctx, unsigned buffers,
 			si_mark_atom_dirty(sctx, &sctx->atoms.s.db_render_state);
 		}
 
-		/* TODO: Find out what's wrong here. Fast depth clear leads to
-		 * corruption in ARK: Survival Evolved, but that may just be
-		 * a coincidence and the root cause is elsewhere.
-		 *
-		 * The corruption can be fixed by putting the DB flush before
-		 * or after the depth clear. (surprisingly)
-		 *
-		 * https://bugs.freedesktop.org/show_bug.cgi?id=102955 (apitrace)
-		 *
-		 * This hack decreases back-to-back ClearDepth performance.
-		 */
-		if ((sctx->db_depth_clear || sctx->db_stencil_clear) &&
-		    sctx->screen->options.clear_db_cache_before_clear)
+		if (needs_db_flush)
 			sctx->flags |= SI_CONTEXT_FLUSH_AND_INV_DB;
 	}