VideoCaptureDeviceLinux: Add support for SPLANE+DMABUF V4L2 type capture

media/video/capture/linux/v4l2_capture_delegate.h

 // Copyright 2015 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.
 
 #ifndef MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_
 #define MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_
 
 #if defined(OS_OPENBSD)
 #include <sys/videoio.h>
 #else
 #include <linux/videodev2.h>
 #endif
 
 #include "base/files/scoped_file.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_vector.h"
 #include "media/video/capture/video_capture_device.h"
 
 namespace media {
 
 // Class doing the actual Linux capture using V4L2 API. V4L2 SPLANE/MPLANE
 // capture specifics are implemented in derived classes. Created and destroyed
 // on the owner's thread, otherwise living and operating on |v4l2_task_runner_|.
 class V4L2CaptureDelegate
     : public base::RefCountedThreadSafe<V4L2CaptureDelegate> {
  public:
-  // Creates the appropiate VideoCaptureDelegate according to parameters.
+  // Creates the appropiate VideoCaptureDelegate according to parameters. The
+  // caller instructs via |allow_using_dma_bufs| if DmaBufs should be used.
   static scoped_refptr<V4L2CaptureDelegate> CreateV4L2CaptureDelegate(
       const VideoCaptureDevice::Name& device_name,
       const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
+      VideoCaptureDevice::Client* client,
+      bool allow_using_dma_bufs,
       int power_line_frequency);
 
   // Retrieves the #planes for a given |fourcc|, or 0 if unknown.
   static size_t GetNumPlanesForFourCc(uint32_t fourcc);
   // Returns the Chrome pixel format for |v4l2_fourcc| or PIXEL_FORMAT_UNKNOWN.
   static VideoPixelFormat V4l2FourCcToChromiumPixelFormat(uint32_t v4l2_fourcc);
 
   // Composes a list of usable and supported pixel formats, in order of
   // preference, with MJPEG prioritised depending on |prefer_mjpeg|.
   static std::list<uint32_t> GetListOfUsableFourCcs(bool prefer_mjpeg);
 
   // Forward-to versions of VideoCaptureDevice virtual methods.
   void AllocateAndStart(int width,
                         int height,
                         float frame_rate,
                         scoped_ptr<VideoCaptureDevice::Client> client);
   void StopAndDeAllocate();
 
   void SetRotation(int rotation);
 
  protected:
-  // Class keeping track of SPLANE/MPLANE V4L2 buffers, mmap()ed on construction
-  // and munmap()ed on destruction. Destruction is syntactically equal for
-  // S/MPLANE but not construction, so this is implemented in derived classes.
+  // Class keeping track of SPLANE/MPLANE V4L2 buffers, mappable or not. Non
+  // mappable buffer keep track of the associated |fd|.
+  // Mappable buffers are mmap()ed on Init() and munmap()ed on destruction.
+  // Destruction is syntactically equal for S/MPLANE but not construction, so
+  // this must be implemented in derived classes.
   // Internally it has a vector of planes, which for SPLANE will contain only
   // one element.
   class BufferTracker : public base::RefCounted<BufferTracker> {
    public:
     BufferTracker();
-    // Abstract method to mmap() given |fd| according to |buffer|, planarity
-    // specific.
+    // Abstract method to init the BufferTracker according to |buffer|.
     virtual bool Init(int fd, const v4l2_buffer& buffer) = 0;
 
     uint8_t* const GetPlaneStart(size_t plane) const {
       DCHECK_LT(plane, planes_.size());
       return planes_[plane].start;
     }
 
+    int const GetPlaneFd(size_t plane) const {
+      DCHECK_LT(plane, planes_.size());
+      return planes_[plane].fd;
+    }
+
     size_t GetPlanePayloadSize(size_t plane) const {
       DCHECK_LT(plane, planes_.size());
       return planes_[plane].payload_size;
     }
 
     void SetPlanePayloadSize(size_t plane, size_t payload_size) {
       DCHECK_LT(plane, planes_.size());
       DCHECK_LE(payload_size, planes_[plane].length);
       planes_[plane].payload_size = payload_size;
     }
 
    protected:
     friend class base::RefCounted<BufferTracker>;
     virtual ~BufferTracker();
     // Adds a given mmap()ed plane to |planes_|.
     void AddMmapedPlane(uint8_t* const start, size_t length);
+    void AddNonMmapedPlane(int fd);
 
    private:
+    // A Plane can be composed of |start| and |length|, for mappable resources
+    // (basically, memory), or by a |fd and a |capture_buffer|, for non mappable
+    // resources (dma-buf).|length| is needed for munmap().
     struct Plane {
       uint8_t* start;
       size_t length;
       size_t payload_size;
+      int fd;
     };
     std::vector<Plane> planes_;
   };
 
   V4L2CaptureDelegate(
       const VideoCaptureDevice::Name& device_name,
       const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
+      v4l2_memory memory_type,
       int power_line_frequency);
   virtual ~V4L2CaptureDelegate();
 
   // Creates the necessary, planarity-specific, internal tracking schemes,
   virtual scoped_refptr<BufferTracker> CreateBufferTracker() const = 0;
 
   // Fill in |format| with the given parameters, in a planarity dependent way.
   virtual bool FillV4L2Format(v4l2_format* format,
                               uint32_t width,
                               uint32_t height,
                               uint32_t pixelformat_fourcc) const = 0;
 
-  // Finish filling |buffer| struct with planarity-dependent data.
-  virtual void FinishFillingV4L2Buffer(v4l2_buffer* buffer) const = 0;
+  // Finish filling |buffer| struct with planarity-dependent data. Underlying
+  // implementation might need to know if it's for enqueueing, to allocate
+  // resources.
+  virtual void FinishFillingV4L2Buffer(v4l2_buffer* buffer,
+                                       bool for_enqueue) const = 0;
 
-  // Fetch the number of bytes occupied by data in |buffer| and set to
-  // |buffer_tracker|.
+  // Set |buffer_tracker|s payload size from |buffer|.
   virtual void SetPayloadSize(
       const scoped_refptr<BufferTracker>& buffer_tracker,
       const v4l2_buffer& buffer) const = 0;
 
   // Sends the captured |buffer| to the |client_|, synchronously.
-  virtual void SendBuffer(
-      const scoped_refptr<BufferTracker>& buffer_tracker,
-      const v4l2_format& format) const = 0;
+  virtual void SendBuffer(const scoped_refptr<BufferTracker>& buffer_tracker,
+                          const v4l2_format& format) const = 0;
 
   // A few accessors for SendBuffer()'s to access private member variables.
   VideoCaptureFormat capture_format() const { return capture_format_; }
   VideoCaptureDevice::Client* client() const { return client_.get(); }
+  v4l2_memory memory_type() const { return memory_type_; }
   int rotation() const { return rotation_; }
 
  private:
   friend class base::RefCountedThreadSafe<V4L2CaptureDelegate>;
 
   // Returns the input |fourcc| as a std::string four char representation.
   static std::string FourccToString(uint32_t fourcc);
   // VIDIOC_QUERYBUFs a buffer from V4L2, creates a BufferTracker for it and
   // enqueues it (VIDIOC_QBUF) back into V4L2.
   bool MapAndQueueBuffer(int index);
   // Fills all common parts of |buffer|. Delegates to FinishFillingV4L2Buffer()
   // for filling in the planar-dependent parts.
-  void FillV4L2Buffer(v4l2_buffer* buffer, int i) const;
+  void FillV4L2Buffer(v4l2_buffer* buffer, int i, bool for_enqueue) const;
   void DoCapture();
   void SetErrorState(const std::string& reason);
 
   const v4l2_buf_type capture_type_;
   const scoped_refptr<base::SingleThreadTaskRunner> v4l2_task_runner_;
   const VideoCaptureDevice::Name device_name_;
   const int power_line_frequency_;
 
   // The following members are only known on AllocateAndStart().
   VideoCaptureFormat capture_format_;
   v4l2_format video_fmt_;
   scoped_ptr<VideoCaptureDevice::Client> client_;
   base::ScopedFD device_fd_;
 
+  // Memory Type (DmaBuf or Mmap) configured on ctor.
+  const v4l2_memory memory_type_;
+
   // Vector of BufferTracker to keep track of mmap()ed pointers and their use.
   std::vector<scoped_refptr<BufferTracker>> buffer_tracker_pool_;
 
   bool is_capturing_;
   int timeout_count_;
 
   // Clockwise rotation in degrees. This value should be 0, 90, 180, or 270.
   int rotation_;
 
   DISALLOW_COPY_AND_ASSIGN(V4L2CaptureDelegate);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_