ozone: Allocate scanout buffer according to KMS modifiers

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/ozone/platform/drm/gpu/hardware_display_controller.h"
 
 #include <drm.h>
 #include <string.h>
 #include <xf86drm.h>
 #include <utility>
@@ skipping 125 matching lines @@
                                                   uint32_t z_order) const {
   for (size_t i = 0; i < crtc_controllers_.size(); ++i) {
     // Make sure all displays have overlay to support this format.
     if (!crtc_controllers_[i]->IsFormatSupported(fourcc_format, z_order))
       return false;
   }
 
   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;
 
   if (is_disabled_)
     return true;
 
   for (const auto& controller : crtc_controllers_)
     status &= controller->SetCursor(buffer);
 
@@ skipping 114 matching lines @@
 
 scoped_refptr<DrmDevice> HardwareDisplayController::GetAllocationDrmDevice()
     const {
   DCHECK(!crtc_controllers_.empty());
   // TODO(dnicoara) When we support mirroring across DRM devices, figure out
   // which device should be used for allocations.
   return crtc_controllers_[0]->drm();
 }
 
 }  // namespace ui