drm: Make DrmDisplayHostManager handle VGEM fd by itself.

ui/ozone/platform/drm/host/drm_display_host_manager.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/host/drm_display_host_manager.h"
 
 #include <fcntl.h>
 #include <stdio.h>
 #include <xf86drm.h>
 
+#include "base/files/file_enumerator.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/threading/worker_pool.h"
 #include "ui/display/types/display_snapshot.h"
 #include "ui/events/ozone/device/device_event.h"
 #include "ui/events/ozone/device/device_manager.h"
 #include "ui/ozone/common/display_util.h"
 #include "ui/ozone/common/gpu/ozone_gpu_messages.h"
 #include "ui/ozone/platform/drm/common/drm_util.h"
 #include "ui/ozone/platform/drm/host/drm_device_handle.h"
 #include "ui/ozone/platform/drm/host/drm_display_host.h"
 #include "ui/ozone/platform/drm/host/drm_gpu_platform_support_host.h"
 #include "ui/ozone/platform/drm/host/drm_native_display_delegate.h"
 
 namespace ui {
 
 namespace {
 
 typedef base::Callback<void(const base::FilePath&, scoped_ptr<DrmDeviceHandle>)>
     OnOpenDeviceReplyCallback;
 
 const char kDefaultGraphicsCardPattern[] = "/dev/dri/card%d";
+const char kVgemDevDriCardPath[] = "/dev/dri/";
+const char kVgemSysCardPath[] = "/sys/bus/platform/devices/vgem/drm/";
 
 const char* kDisplayActionString[] = {
     "ADD",
     "REMOVE",
     "CHANGE",
 };
 
 void OpenDeviceOnWorkerThread(
     const base::FilePath& path,
     const scoped_refptr<base::TaskRunner>& reply_runner,
@@ skipping 24 matching lines @@
     if (ret == 0 && res.count_crtcs > 0) {
       return base::FilePath(card_path);
     }
 
     VPLOG_IF(1, ret) << "Failed to get DRM resources for '" << card_path << "'";
   }
 
   return base::FilePath();
 }
 
+base::FilePath GetVgemCardPath() {
+  base::FileEnumerator file_iter(
+      base::FilePath::FromUTF8Unsafe(kVgemSysCardPath), false,

[spang, 2015/06/03 19:03:21]

I don't think you need the FromUTF8Unsafe(). Does
base::FilePath(kVgemSysCardPath) not work?

+      base::FileEnumerator::DIRECTORIES, FILE_PATH_LITERAL("card*"));
+
+  while (!file_iter.Next().empty()) {
+    // Inspect the card%d directories in the directory and extract the filename.
+    std::string vgem_card_path =
+        kVgemDevDriCardPath +
+        file_iter.GetInfo().GetName().BaseName().MaybeAsASCII();

[spang, 2015/06/03 19:03:21]

Use value() instead of MaybeAsASCII().

[dshwang, 2015/06/04 08:32:07]

Done.

+    DVLOG(1) << "VGEM card path is " << vgem_card_path;
+    return base::FilePath(vgem_card_path);
+  }
+  DVLOG(1) << "Don't support VGEM";
+  return base::FilePath();
+}
+
 class FindDrmDisplayHostById {
  public:
   explicit FindDrmDisplayHostById(int64_t display_id)
       : display_id_(display_id) {}
 
   bool operator()(const DrmDisplayHost* display) const {
     return display->snapshot()->display_id() == display_id_;
   }
 
  private:
@@ skipping 15 matching lines @@
     // First device needs to be treated specially. We need to open this
     // synchronously since the GPU process will need it to initialize the
     // graphics state.
     base::ThreadRestrictions::ScopedAllowIO allow_io;
     primary_drm_device_handle_.reset(new DrmDeviceHandle());
     if (!primary_drm_device_handle_->Initialize(primary_graphics_card_path_)) {
       LOG(FATAL) << "Failed to open primary graphics card";
       return;
     }
     drm_devices_.insert(primary_graphics_card_path_);
+
+    vgem_card_path_ = GetVgemCardPath();
+    if (!vgem_card_path_.empty()) {

[dshwang, 2015/06/03 10:07:35]

handle the platform which doesn't have vgem.

[spang, 2015/06/03 19:03:21]

Can you just use open() and store it in a ScopedFD?

I don't think we should use base::File - it's an unnecessary abstraction. In
this case we can assume linux.

We should also log if open() fails:

  PLOG(ERROR) << "Failed to open vgem: " << vgem_card_path_.value();

[dshwang, 2015/06/04 08:32:07]

Done.

+      vgem_card_device_file_ = base::File(
+          vgem_card_path_, base::File::FLAG_OPEN | base::File::FLAG_READ |
+                               base::File::FLAG_WRITE);
+    }
   }
 
   device_manager_->AddObserver(this);
   proxy_->RegisterHandler(this);
 
   ScopedVector<HardwareDisplayControllerInfo> display_infos =
       GetAvailableDisplayControllerInfos(primary_drm_device_handle_->fd());
   has_dummy_display_ = !display_infos.empty();
   for (size_t i = 0; i < display_infos.size(); ++i) {
     displays_.push_back(new DrmDisplayHost(
@@ skipping 56 matching lines @@
 }
 
 void DrmDisplayHostManager::ProcessEvent() {
   while (!event_queue_.empty() && !task_pending_) {
     DisplayEvent event = event_queue_.front();
     event_queue_.pop();
     VLOG(1) << "Got display event " << kDisplayActionString[event.action_type]
             << " for " << event.path.value();
     switch (event.action_type) {
       case DeviceEvent::ADD:
+        if (event.path == vgem_card_path_)
+          continue;
         if (drm_devices_.find(event.path) == drm_devices_.end()) {
           task_pending_ = base::WorkerPool::PostTask(
               FROM_HERE,
               base::Bind(&OpenDeviceOnWorkerThread, event.path,
                          base::ThreadTaskRunnerHandle::Get(),
                          base::Bind(&DrmDisplayHostManager::OnAddGraphicsDevice,
                                     weak_ptr_factory_.GetWeakPtr())),
               false /* task_is_slow */);
         }
         break;
       case DeviceEvent::CHANGE:
         task_pending_ = base::ThreadTaskRunnerHandle::Get()->PostTask(
             FROM_HERE,
             base::Bind(&DrmDisplayHostManager::OnUpdateGraphicsDevice,
                        weak_ptr_factory_.GetWeakPtr()));
         break;
       case DeviceEvent::REMOVE:
         DCHECK(event.path != primary_graphics_card_path_)
             << "Removing primary graphics card";
+        DCHECK(event.path != vgem_card_path_) << "Removing VGEM device";
         auto it = drm_devices_.find(event.path);
         if (it != drm_devices_.end()) {
           task_pending_ = base::ThreadTaskRunnerHandle::Get()->PostTask(
               FROM_HERE,
               base::Bind(&DrmDisplayHostManager::OnRemoveGraphicsDevice,
                          weak_ptr_factory_.GetWeakPtr(), event.path));
           drm_devices_.erase(it);
         }
         break;
     }
@@ skipping 141 matching lines @@
 
   callback.Run(snapshots);
 }
 
 void DrmDisplayHostManager::NotifyDisplayDelegate() const {
   if (delegate_)
     delegate_->OnConfigurationChanged();
 }
 
 }  // namespace ui