drm/i915: Replace last_[rwf]_seqno with last_[rwf]_req

The object structure contains the last read, write and fenced seqno values for
use in syncrhonisation operations. These have now been replaced with their
request structure counterparts.

Note that to ensure that objects do not end up with dangling pointers, the
assignments of last_*_req include reference count updates. Thus a request cannot
be freed if an object is still hanging on to it for any reason.

v2: Corrected 'last_rendering_' to 'last_read_' in a number of comments that did
not get updated when 'last_rendering_seqno' became 'last_read|write_seqno'
several millenia ago.

For: VIZ-4377
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Thomas Daniel <Thomas.Daniel@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 48c0c4a60364..4924f1d3d4b4 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1944,10 +1944,10 @@ struct drm_i915_gem_object {
         struct intel_engine_cs *ring;
 
         /** Breadcrumb of last rendering to the buffer. */
-        uint32_t last_read_seqno;
-        uint32_t last_write_seqno;
+        struct drm_i915_gem_request *last_read_req;
+        struct drm_i915_gem_request *last_write_req;
         /** Breadcrumb of last fenced GPU access to the buffer. */
-        uint32_t last_fenced_seqno;
+        struct drm_i915_gem_request *last_fenced_req;
 
         /** Current tiling stride for the object, if it's tiled. */
         uint32_t stride;
@@ -1986,9 +1986,10 @@ void i915_gem_track_fb(struct drm_i915_gem_object *old,
  * The request queue allows us to note sequence numbers that have been emitted
  * and may be associated with active buffers to be retired.
  *
- * By keeping this list, we can avoid having to do questionable
- * sequence-number comparisons on buffer last_rendering_seqnos, and associate
- * an emission time with seqnos for tracking how far ahead of the GPU we are.
+ * By keeping this list, we can avoid having to do questionable sequence
+ * number comparisons on buffer last_read|write_seqno. It also allows an
+ * emission time to be associated with the request for tracking how far ahead
+ * of the GPU the submission is.
  */
 struct drm_i915_gem_request {
         struct kref ref;