[Mesa-dev] [PATCH 2/3] radeon: use staging for mapping linear textures

[Grigori Goronzy]

Textures that likely reside in VRAM, are mapped for reading and
don't require direct mapping should be staged into GTT, to avoid bad
performance. This fixes readback performance of VDPAU surfaces.
---
 src/gallium/drivers/radeon/r600_texture.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/gallium/drivers/radeon/r600_texture.c b/src/gallium/drivers/radeon/r600_texture.c
index ebb70906..9ba1e36 100644
--- a/src/gallium/drivers/radeon/r600_texture.c
+++ b/src/gallium/drivers/radeon/r600_texture.c
@@ -852,6 +852,12 @@ static void *r600_texture_transfer_map(struct pipe_context *ctx,
 	if (rtex->surface.level[level].mode >= RADEON_SURF_MODE_1D)
 		use_staging_texture = TRUE;
 
+	/* Untiled buffers in VRAM, which is slow for CPU reads */
+	if ((usage & PIPE_TRANSFER_READ) && !(usage & PIPE_TRANSFER_MAP_DIRECTLY) &&
+	    (rtex->resource.domains == RADEON_DOMAIN_VRAM)) {
+		use_staging_texture = TRUE;
+	}
+
 	/* Use a staging texture for uploads if the underlying BO is busy. */
 	if (!(usage & PIPE_TRANSFER_READ) &&
 	    (r600_rings_is_buffer_referenced(rctx, rtex->resource.cs_buf, RADEON_USAGE_READWRITE) ||
-- 
1.8.1.2