Add support for multiple V4L2 video devices of the same type.

media/gpu/generic_v4l2_device.h

 // 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.
 //
 // This file contains the implementation of GenericV4L2Device used on
 // platforms, which provide generic V4L2 video codec devices.
 
 #ifndef MEDIA_GPU_GENERIC_V4L2_DEVICE_H_
 #define MEDIA_GPU_GENERIC_V4L2_DEVICE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
+#include <map>
+
 #include "base/files/scoped_file.h"
 #include "base/macros.h"
 #include "media/gpu/v4l2_device.h"
 
 namespace media {
 
 class GenericV4L2Device : public V4L2Device {
  public:
   explicit GenericV4L2Device(Type type);
 
+  bool Initialize() override;

[kcwu, 2016/10/06 10:39:59]

Why put line 26 and 28 before line 30?

[Pawel Osciak, 2016/10/07 08:30:23]

Ah right, good point.

+
+  bool Open(uint32_t v4l2_pixfmt) override;
+
   // V4L2Device implementation.
   int Ioctl(int request, void* arg) override;
   bool Poll(bool poll_device, bool* event_pending) override;
   bool SetDevicePollInterrupt() override;
   bool ClearDevicePollInterrupt() override;
   void* Mmap(void* addr,
              unsigned int len,
              int prot,
              int flags,
              unsigned int offset) override;
   void Munmap(void* addr, unsigned int len) override;
-  bool Initialize() override;
 
   std::vector<base::ScopedFD> GetDmabufsForV4L2Buffer(
       int index,
       size_t num_planes,
       enum v4l2_buf_type type) override;
 
   bool CanCreateEGLImageFrom(uint32_t v4l2_pixfmt) override;
   EGLImageKHR CreateEGLImage(
       EGLDisplay egl_display,
       EGLContext egl_context,
       GLuint texture_id,
       const gfx::Size& size,
       unsigned int buffer_index,
       uint32_t v4l2_pixfmt,
       const std::vector<base::ScopedFD>& dmabuf_fds) override;
 
   EGLBoolean DestroyEGLImage(EGLDisplay egl_display,
                              EGLImageKHR egl_image) override;
   GLenum GetTextureTarget() override;
   uint32_t PreferredInputFormat() override;
 
+  std::vector<uint32_t> GetSupportedImageProcessorPixelformats(
+      v4l2_buf_type buf_type) override;
+
+  VideoDecodeAccelerator::SupportedProfiles GetSupportedDecodeProfiles(
+      const size_t num_formats,
+      const uint32_t pixelformats[]) override;
+
+  VideoEncodeAccelerator::SupportedProfiles GetSupportedEncodeProfiles()
+      override;
+
+  bool IsJpegDecodingSupported() override;
+
  private:
+  // Vector of video device node paths and corresponding pixelformats supported
+  // by each device node.
+  using Devices = std::vector<std::pair<std::string, std::vector<uint32_t>>>;
+
   ~GenericV4L2Device() override;
 
+  // Open device node for |path|.
+  bool OpenDevicePath(const std::string& path);
+
+  // Close the currently open device.
+  void CloseDevice();
+
+  // Enumerate all V4L2 devices on the system for |type| and store the results
+  // under devices_by_type_[type].
+  void EnumerateDevicesForType(V4L2Device::Type type);
+
+  // Return device information for all devices of |type| available in the
+  // system. Enumerates and queries devices on first run and caches the results
+  // for subsequent calls.
+  const Devices& GetDevicesForType(V4L2Device::Type type);
+
+  // Return device node path for device of |type| supporting |pixfmt|, or
+  // an empty string if the given combination is not supported by the system.
+  std::string GetDevicePathFor(V4L2Device::Type type, uint32_t pixfmt);
+
+  // Stores information for all devices available on the system
+  // for each device Type.
+  std::map<V4L2Device::Type, Devices> devices_by_type_;
+
   // The actual device fd.
   base::ScopedFD device_fd_;
 
   // eventfd fd to signal device poll thread when its poll() should be
   // interrupted.
   base::ScopedFD device_poll_interrupt_fd_;
 
 #if USE_LIBV4L2
   // Use libv4l2 when operating |device_fd_|.
   bool use_libv4l2_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(GenericV4L2Device);
 
   // Lazily initialize static data after sandbox is enabled.  Return false on
   // init failure.
   static bool PostSandboxInitialization();
 };
 }  //  namespace media
 
 #endif  // MEDIA_GPU_GENERIC_V4L2_DEVICE_H_