drm/i915: Return a mask of the active rings in the high word of busy_ioctl
The intention is to help select which engine to use for copies with
interoperating clients - such as a GL client making a request to the X
server to perform a SwapBuffers, which may require copying from the
active GL back buffer to the X front buffer.
We choose to report a mask of the active rings to future proof the
interface against any changes which may allow for the object to reside
upon multiple rings.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: bikeshed away the write ring mask and add the explanation
Chris sent in a follow-up mail why we decided to use masks.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index b923b03..0f149fe 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -704,7 +704,11 @@
/** Handle of the buffer to check for busy */
__u32 handle;
- /** Return busy status (1 if busy, 0 if idle) */
+ /** Return busy status (1 if busy, 0 if idle).
+ * The high word is used to indicate on which rings the object
+ * currently resides:
+ * 16:31 - busy (r or r/w) rings (16 render, 17 bsd, 18 blt, etc)
+ */
__u32 busy;
};