ozone: Allocate scanout buffer according to KMS modifiers

ui/ozone/platform/drm/gpu/hardware_display_controller.cc

Index: ui/ozone/platform/drm/gpu/hardware_display_controller.cc
diff --git a/ui/ozone/platform/drm/gpu/hardware_display_controller.cc b/ui/ozone/platform/drm/gpu/hardware_display_controller.cc
index c45ed81146759ef83c64fe507846e9ef399d2ea8..3bebdedf280c77dc209e0962d2fef7f460259a4d 100644
--- a/ui/ozone/platform/drm/gpu/hardware_display_controller.cc
+++ b/ui/ozone/platform/drm/gpu/hardware_display_controller.cc
@@ -143,6 +143,16 @@ bool HardwareDisplayController::IsFormatSupported(uint32_t fourcc_format,
   return true;
 }
 
+std::vector<uint64_t> HardwareDisplayController::GetFormatModifiers(
+    uint32_t format) {
+  // TODO(hoegsberg): We need to intersect modifiers from different

[dnicoara, 2016/12/19 19:44:46]

I'm wondering what are the implications of not implementing this TODO right now
on existing platforms? Could this cause regressions?

[marcheu1, 2016/12/20 01:25:30]

I thought right now there should be none since we are hopefully allocating
buffers for evdi or udl on a different instance?

[dnicoara, 2016/12/20 15:35:42]

Yes, I believe we do software mirror for evdi and udl.

Just wanted to confirm that this doesn't apply to existing devices. Thank you
for confirming.

[hoegsberg1, 2016/12/22 23:05:20]

It looks like a HardwareDisplayController will have multiple CrtcControllers
when we're doing mirror mode. In that case we need to make sure we allocate a
buffer that works for all actual CRTCs in the HardwareDisplayController. In case
of kevin, one CRTC will support AFBC while the other wont. Intersecting the sets
here means that we'll drop the AFBC modifier, since it's not in both sets.

+  // controllers here.
+  for (const auto& controller : crtc_controllers_)

[Daniele Castagna, 2016/12/20 18:03:28]

nit: maybe
  if (!crtc_controllers_.empty())
    return crtc_controllers_->front()->GetFormatModifiers(format)

[hoegsberg1, 2016/12/22 23:05:20]

I added the intersection code instead.

+    return controller->GetFormatModifiers(format);
+
+  return std::vector<uint64_t>();
+}
+
 bool HardwareDisplayController::SetCursor(
     const scoped_refptr<ScanoutBuffer>& buffer) {
   bool status = true;