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/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 5c4657a54f977689c1668a9a70b8a8f6e39743c9..4be096068b35283ddb469a4d82c07ba60b6b5586 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3400,6 +3400,10 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
        ret = i915_gem_object_flush_active(obj);
 
        args->busy = obj->active;
+       if (obj->ring) {
+               BUILD_BUG_ON(I915_NUM_RINGS > 16);
+               args->busy |= intel_ring_flag(obj->ring) << 16;
+       }
 
        drm_gem_object_unreference(&obj->base);
 unlock:

diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index b923b032743f0080990aaf98de0c923c48856081..0f149fe32211aebaf1ceb0c339b94cdc3cd907b4 100644 (file)
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -704,7 +704,11 @@ struct drm_i915_gem_busy {
        /** 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;
 };