[Mesa-dev] [PATCH] r600g/compute: Add a work-around for flushing issues on Cayman

[Tom Stellard]

From: Tom Stellard <thomas.stellard at amd.com>

https://bugs.freedesktop.org/show_bug.cgi?id=69321

CC: "10.0" <mesa-stable at lists.freedesktop.org>
---
 src/gallium/drivers/r600/evergreen_compute.c |  4 ++++
 src/gallium/drivers/r600/r600_hw_context.c   |  4 +++-
 src/gallium/drivers/r600/r600_pipe.h         | 10 ++++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/r600/evergreen_compute.c b/src/gallium/drivers/r600/evergreen_compute.c
index ffdc5c3..d668c8e 100644
--- a/src/gallium/drivers/r600/evergreen_compute.c
+++ b/src/gallium/drivers/r600/evergreen_compute.c
@@ -474,6 +474,10 @@ static void compute_emit_cs(struct r600_context *ctx, const uint *block_layout,
 	r600_flush_emit(ctx);
 	ctx->b.flags = 0;
 
+	if (ctx->b.chip_class >= CAYMAN) {
+		ctx->skip_surface_sync_on_next_cs_flush = true;
+	}
+
 #if 0
 	COMPUTE_DBG(ctx->screen, "cdw: %i\n", cs->cdw);
 	for (i = 0; i < cs->cdw; i++) {
diff --git a/src/gallium/drivers/r600/r600_hw_context.c b/src/gallium/drivers/r600/r600_hw_context.c
index 5f3a9bd..191a81d 100644
--- a/src/gallium/drivers/r600/r600_hw_context.c
+++ b/src/gallium/drivers/r600/r600_hw_context.c
@@ -293,7 +293,7 @@ void r600_flush_emit(struct r600_context *rctx)
 				S_0085F0_SMX_ACTION_ENA(1);
 	}
 
-	if (cp_coher_cntl) {
+	if (cp_coher_cntl && !rctx->skip_surface_sync_on_next_cs_flush) {
 		cs->buf[cs->cdw++] = PKT3(PKT3_SURFACE_SYNC, 3, 0);
 		cs->buf[cs->cdw++] = cp_coher_cntl;   /* CP_COHER_CNTL */
 		cs->buf[cs->cdw++] = 0xffffffff;      /* CP_COHER_SIZE */
@@ -354,6 +354,8 @@ void r600_context_flush(struct r600_context *ctx, unsigned flags)
 
 	/* Flush the CS. */
 	ctx->b.ws->cs_flush(ctx->b.rings.gfx.cs, flags, ctx->screen->cs_count++);
+
+	ctx->skip_surface_sync_on_next_cs_flush = false;
 }
 
 void r600_begin_new_cs(struct r600_context *ctx)
diff --git a/src/gallium/drivers/r600/r600_pipe.h b/src/gallium/drivers/r600/r600_pipe.h
index d7af618..f0d4be4 100644
--- a/src/gallium/drivers/r600/r600_pipe.h
+++ b/src/gallium/drivers/r600/r600_pipe.h
@@ -507,6 +507,16 @@ struct r600_context {
 
 	void				*sb_context;
 	struct r600_isa		*isa;
+
+	/* Work-around for flushing problems with compute shaders on Cayman:
+	 * Emitting a SURFACE_SYNC packet with any of the CB*_DEST_BASE_ENA
+	 * or DB_DEST_BASE_ENA bits set after dispatching a compute shader
+	 * hangs the GPU.
+	 *
+	 * Setting this to true will prevent r600_flush_emit() from emitting
+	 * a SURFACE_SYNC packet.  This field will be cleared by
+	 * by r600_context_flush() after flushing the command stream. */
+	boolean				skip_surface_sync_on_next_cs_flush;
 };
 
 static INLINE void r600_emit_command_buffer(struct radeon_winsys_cs *cs,
-- 
1.8.1.5