r600g/radeonsi: Reduce or even drop special treatment of persistent mappings

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

diff --git a/src/gallium/drivers/radeon/r600_buffer_common.c b/src/gallium/drivers/radeon/r600_buffer_common.c
index 4e6b897..154c33d 100644 (file)
--- a/src/gallium/drivers/radeon/r600_buffer_common.c
+++ b/src/gallium/drivers/radeon/r600_buffer_common.c
@@ -127,13 +127,17 @@ bool r600_init_resource(struct r600_common_screen *rscreen,
                break;
        }
 
-       /* Use GTT for all persistent mappings, because they are
-        * always cached and coherent. */
-       if (res->b.b.target == PIPE_BUFFER &&
+       /* Use GTT for all persistent mappings with older kernels, because they
+        * didn't always flush the HDP cache before CS execution.
+        *
+        * Write-combined CPU mappings are fine, the kernel ensures all CPU
+        * writes finish before the GPU executes a command stream.
+        */
+       if (rscreen->info.drm_minor < 40 &&
+           res->b.b.target == PIPE_BUFFER &&
            res->b.b.flags & (PIPE_RESOURCE_FLAG_MAP_PERSISTENT |
                              PIPE_RESOURCE_FLAG_MAP_COHERENT)) {
                res->domains = RADEON_DOMAIN_GTT;
-               flags = 0;
        }
 
        /* Tiled textures are unmappable. Always put them in VRAM. */