[PATCH 4/5] drm/vmwgfx: Disable command buffers on svga3 without gbobjects

[Zack Rusin]

From: Zack Rusin <zackr at vmware.com>

With very limited vram on svga3 it's difficult to handle all the surface
migrations. Without gbobjects, i.e. the ability to store surfaces in
guest mobs, there's no reason to support intermediate svga2 features,
especially because we can fall back to fb traces and svga3 will never
support those in-between features.

On svga3 we wither want to use fb traces or screen targets
(i.e. gbobjects), nothing in between. This fixes presentation on a lot
of fusion/esxi tech previews where the exposed svga3 caps haven't been
finalized yet.

Signed-off-by: Zack Rusin <zackr at vmware.com>
Fixes: 2cd80dbd3551 ("drm/vmwgfx: Add basic support for SVGA3")
Cc: <stable at vger.kernel.org> # v5.14+
Reviewed-by: Martin Krastev <krastevm at vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_cmd.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_cmd.c b/drivers/gpu/drm/vmwgfx/vmwgfx_cmd.c
index bf1b394753da..162dfeb1cc5a 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_cmd.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_cmd.c
@@ -675,11 +675,14 @@ int vmw_cmd_emit_dummy_query(struct vmw_private *dev_priv,
  */
 bool vmw_cmd_supported(struct vmw_private *vmw)
 {
-	if ((vmw->capabilities & (SVGA_CAP_COMMAND_BUFFERS |
-				  SVGA_CAP_CMD_BUFFERS_2)) != 0)
-		return true;
+	bool has_cmdbufs =
+		(vmw->capabilities & (SVGA_CAP_COMMAND_BUFFERS |
+				      SVGA_CAP_CMD_BUFFERS_2)) != 0;
+	if (vmw_is_svga_v3(vmw))
+		return (has_cmdbufs &&
+			(vmw->capabilities & SVGA_CAP_GBOBJECTS) != 0);
 	/*
 	 * We have FIFO cmd's
 	 */
-	return vmw->fifo_mem != NULL;
+	return has_cmdbufs || vmw->fifo_mem != NULL;
 }
-- 
2.32.0