[PATCH hwc v1 6/6] drm_hwcomposer: Add out-fence support

[Robert Foss]

Add support for out-fences through the OUT_FENCE_PTR property.
Out-fences signal when their associated buffer may be read by a device.

Signed-off-by: Robert Foss <robert.foss at collabora.com>
---
 drmdisplaycomposition.h  |  9 +++++++++
 drmdisplaycompositor.cpp | 16 ++++++++++++++++
 drmhwctwo.cpp            |  9 ++-------
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/drmdisplaycomposition.h b/drmdisplaycomposition.h
index b165adc..0586d58 100644
--- a/drmdisplaycomposition.h
+++ b/drmdisplaycomposition.h
@@ -189,6 +189,14 @@ class DrmDisplayComposition {
     return planner_;
   }
 
+  int take_out_fence() {
+    return out_fence_.Release();
+  }
+
+  void set_out_fence(int out_fence) {
+    out_fence_.Set(dup(out_fence));
+  }
+
   void Dump(std::ostringstream *out) const;
 
  private:
@@ -215,6 +223,7 @@ class DrmDisplayComposition {
   int timeline_current_ = 0;
   int timeline_squash_done_ = 0;
   int timeline_pre_comp_done_ = 0;
+  UniqueFd out_fence_ = -1;
 
   bool geometry_changed_;
   std::vector<DrmHwcLayer> layers_;
diff --git a/drmdisplaycompositor.cpp b/drmdisplaycompositor.cpp
index 71c0451..251cdb5 100644
--- a/drmdisplaycompositor.cpp
+++ b/drmdisplaycompositor.cpp
@@ -492,6 +492,7 @@ int DrmDisplayCompositor::CommitFrame(DrmDisplayComposition *display_comp,
       display_comp->composition_planes();
   std::vector<DrmCompositionRegion> &pre_comp_regions =
       display_comp->pre_comp_regions();
+  uint64_t out_fences[drm_->GetCrtcCount()];
 
   DrmConnector *connector = drm_->GetConnectorForDisplay(display_);
   if (!connector) {
@@ -510,6 +511,16 @@ int DrmDisplayCompositor::CommitFrame(DrmDisplayComposition *display_comp,
     return -ENOMEM;
   }
 
+  if (crtc->out_fence_ptr_property().id() != 0) {
+    ret = drmModeAtomicAddProperty(pset, crtc->id(), crtc->out_fence_ptr_property().id(),
+                                   (uint64_t) &out_fences[0]);
+    if (ret < 0) {
+      ALOGE("Failed to add OUT_FENCE_PTR property to pset: %d", ret);
+      drmModeAtomicFree(pset);
+      return ret;
+    }
+  }
+
   if (mode_.needs_modeset) {
     ret = drmModeAtomicAddProperty(pset, crtc->id(), crtc->mode_property().id(),
                                    mode_.blob_id) < 0 ||
@@ -708,6 +719,11 @@ out:
     mode_.needs_modeset = false;
   }
 
+  if (crtc->out_fence_ptr_property().id()) {
+    display_comp->set_out_fence((int) out_fences[crtc->pipe()]);
+    close((int) out_fences[crtc->pipe()]);
+  }
+
   return ret;
 }
 
diff --git a/drmhwctwo.cpp b/drmhwctwo.cpp
index 762ee8c..89399bf 100644
--- a/drmhwctwo.cpp
+++ b/drmhwctwo.cpp
@@ -557,19 +557,14 @@ HWC2::Error DrmHwcTwo::HwcDisplay::PresentDisplay(int32_t *retire_fence) {
     i = overlay_planes.erase(i);
   }
 
+  AddFenceToRetireFence(composition->take_out_fence());
+
   ret = compositor_.ApplyComposition(std::move(composition));
   if (ret) {
     ALOGE("Failed to apply the frame composition ret=%d", ret);
     return HWC2::Error::BadParameter;
   }
 
-  // Now that the release fences have been generated by the compositor, make
-  // sure they're managed properly
-  for (std::pair<const uint32_t, DrmHwcTwo::HwcLayer *> &l : z_map) {
-    l.second->manage_release_fence();
-    AddFenceToRetireFence(l.second->release_fence());
-  }
-
   // The retire fence returned here is for the last frame, so return it and
   // promote the next retire fence
   *retire_fence = retire_fence_.Release();
-- 
2.11.0