modules/camera/3_4/v4l2_wrapper.cpp

/*
 * Copyright 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "v4l2_wrapper.h"

#include <algorithm>
#include <array>
#include <limits>
#include <mutex>
#include <vector>

#include <fcntl.h>
#include <linux/videodev2.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <android-base/unique_fd.h>

#include "common.h"
#include "stream_format.h"
#include "v4l2_gralloc.h"

namespace v4l2_camera_hal {

const int32_t kStandardSizes[][2] = {{640, 480}, {320, 240}};

V4L2Wrapper* V4L2Wrapper::NewV4L2Wrapper(const std::string device_path) {
  std::unique_ptr<V4L2Gralloc> gralloc(V4L2Gralloc::NewV4L2Gralloc());
  if (!gralloc) {
    HAL_LOGE("Failed to initialize gralloc helper.");
    return nullptr;
  }

  return new V4L2Wrapper(device_path, std::move(gralloc));
}

V4L2Wrapper::V4L2Wrapper(const std::string device_path,
                         std::unique_ptr<V4L2Gralloc> gralloc)
    : device_path_(std::move(device_path)),
      gralloc_(std::move(gralloc)),
      connection_count_(0) {}

V4L2Wrapper::~V4L2Wrapper() {}

int V4L2Wrapper::Connect() {
  HAL_LOG_ENTER();
  std::lock_guard<std::mutex> lock(connection_lock_);

  if (connected()) {
    HAL_LOGV("Camera device %s is already connected.", device_path_.c_str());
    ++connection_count_;
    return 0;
  }

  // Open in nonblocking mode (DQBUF may return EAGAIN).
  int fd = TEMP_FAILURE_RETRY(open(device_path_.c_str(), O_RDWR | O_NONBLOCK));
  if (fd < 0) {
    HAL_LOGE("failed to open %s (%s)", device_path_.c_str(), strerror(errno));
    return -ENODEV;
  }
  device_fd_.reset(fd);
  ++connection_count_;

  // Check if this connection has the extended control query capability.
  v4l2_query_ext_ctrl query;
  query.id = V4L2_CTRL_FLAG_NEXT_CTRL | V4L2_CTRL_FLAG_NEXT_COMPOUND;
  extended_query_supported_ = (IoctlLocked(VIDIOC_QUERY_EXT_CTRL, &query) == 0);

  // TODO(b/29185945): confirm this is a supported device.
  // This is checked by the HAL, but the device at device_path_ may
  // not be the same one that was there when the HAL was loaded.
  // (Alternatively, better hotplugging support may make this unecessary
  // by disabling cameras that get disconnected and checking newly connected
  // cameras, so Connect() is never called on an unsupported camera)
  return 0;
}

void V4L2Wrapper::Disconnect() {
  HAL_LOG_ENTER();
  std::lock_guard<std::mutex> lock(connection_lock_);

  if (connection_count_ == 0) {
    // Not connected.
    HAL_LOGE("Camera device %s is not connected, cannot disconnect.",
             device_path_.c_str());
    return;
  }

  --connection_count_;
  if (connection_count_ > 0) {
    HAL_LOGV("Disconnected from camera device %s. %d connections remain.",
             device_path_.c_str());
    return;
  }

  device_fd_.reset(-1);  // Includes close().
  format_.reset();
  buffers_.clear();
  // Closing the device releases all queued buffers back to the user.
  gralloc_->unlockAllBuffers();
}

// Helper function. Should be used instead of ioctl throughout this class.
template <typename T>
int V4L2Wrapper::IoctlLocked(int request, T data) {
  // Potentially called so many times logging entry is a bad idea.
  std::lock_guard<std::mutex> lock(device_lock_);

  if (!connected()) {
    HAL_LOGE("Device %s not connected.", device_path_.c_str());
    return -ENODEV;
  }
  return TEMP_FAILURE_RETRY(ioctl(device_fd_.get(), request, data));
}

int V4L2Wrapper::StreamOn() {
  if (!format_) {
    HAL_LOGE("Stream format must be set before turning on stream.");
    return -EINVAL;
  }

  int32_t type = format_->type();
  if (IoctlLocked(VIDIOC_STREAMON, &type) < 0) {
    HAL_LOGE("STREAMON fails: %s", strerror(errno));
    return -ENODEV;
  }

  HAL_LOGV("Stream turned on.");
  return 0;
}

int V4L2Wrapper::StreamOff() {
  if (!format_) {
    // Can't have turned on the stream without format being set,
    // so nothing to turn off here.
    return 0;
  }

  int32_t type = format_->type();
  int res = IoctlLocked(VIDIOC_STREAMOFF, &type);
  // Calling STREAMOFF releases all queued buffers back to the user.
  int gralloc_res = gralloc_->unlockAllBuffers();
  // No buffers in flight.
  for (size_t i = 0; i < buffers_.size(); ++i) {
    buffers_[i] = false;
  }
  if (res < 0) {
    HAL_LOGE("STREAMOFF fails: %s", strerror(errno));
    return -ENODEV;
  }
  if (gralloc_res < 0) {
    HAL_LOGE("Failed to unlock all buffers after turning stream off.");
    return gralloc_res;
  }

  HAL_LOGV("Stream turned off.");
  return 0;
}

int V4L2Wrapper::QueryControl(uint32_t control_id,
                              v4l2_query_ext_ctrl* result) {
  int res;

  memset(result, 0, sizeof(*result));

  if (extended_query_supported_) {
    result->id = control_id;
    res = IoctlLocked(VIDIOC_QUERY_EXT_CTRL, result);
    // Assuming the operation was supported (not ENOTTY), no more to do.
    if (errno != ENOTTY) {
      if (res) {
        HAL_LOGE("QUERY_EXT_CTRL fails: %s", strerror(errno));
        return -ENODEV;
      }
      return 0;
    }
  }

  // Extended control querying not supported, fall back to basic control query.
  v4l2_queryctrl query;
  query.id = control_id;
  if (IoctlLocked(VIDIOC_QUERYCTRL, &query)) {
    HAL_LOGE("QUERYCTRL fails: %s", strerror(errno));
    return -ENODEV;
  }

  // Convert the basic result to the extended result.
  result->id = query.id;
  result->type = query.type;
  memcpy(result->name, query.name, sizeof(query.name));
  result->minimum = query.minimum;
  if (query.type == V4L2_CTRL_TYPE_BITMASK) {
    // According to the V4L2 documentation, when type is BITMASK,
    // max and default should be interpreted as __u32. Practically,
    // this means the conversion from 32 bit to 64 will pad with 0s not 1s.
    result->maximum = static_cast<uint32_t>(query.maximum);
    result->default_value = static_cast<uint32_t>(query.default_value);
  } else {
    result->maximum = query.maximum;
    result->default_value = query.default_value;
  }
  result->step = static_cast<uint32_t>(query.step);
  result->flags = query.flags;
  result->elems = 1;
  switch (result->type) {
    case V4L2_CTRL_TYPE_INTEGER64:
      result->elem_size = sizeof(int64_t);
      break;
    case V4L2_CTRL_TYPE_STRING:
      result->elem_size = result->maximum + 1;
      break;
    default:
      result->elem_size = sizeof(int32_t);
      break;
  }

  return 0;
}

int V4L2Wrapper::GetControl(uint32_t control_id, int32_t* value) {
  // For extended controls (any control class other than "user"),
  // G_EXT_CTRL must be used instead of G_CTRL.
  if (V4L2_CTRL_ID2CLASS(control_id) != V4L2_CTRL_CLASS_USER) {
    v4l2_ext_control control;
    v4l2_ext_controls controls;
    memset(&control, 0, sizeof(control));
    memset(&controls, 0, sizeof(controls));

    control.id = control_id;
    controls.ctrl_class = V4L2_CTRL_ID2CLASS(control_id);
    controls.count = 1;
    controls.controls = &control;

    if (IoctlLocked(VIDIOC_G_EXT_CTRLS, &controls) < 0) {
      HAL_LOGE("G_EXT_CTRLS fails: %s", strerror(errno));
      return -ENODEV;
    }
    *value = control.value;
  } else {
    v4l2_control control{control_id, 0};
    if (IoctlLocked(VIDIOC_G_CTRL, &control) < 0) {
      HAL_LOGE("G_CTRL fails: %s", strerror(errno));
      return -ENODEV;
    }
    *value = control.value;
  }
  return 0;
}

int V4L2Wrapper::SetControl(uint32_t control_id,
                            int32_t desired,
                            int32_t* result) {
  int32_t result_value = 0;

  // TODO(b/29334616): When async, this may need to check if the stream
  // is on, and if so, lock it off while setting format. Need to look
  // into if V4L2 supports adjusting controls while the stream is on.

  // For extended controls (any control class other than "user"),
  // S_EXT_CTRL must be used instead of S_CTRL.
  if (V4L2_CTRL_ID2CLASS(control_id) != V4L2_CTRL_CLASS_USER) {
    v4l2_ext_control control;
    v4l2_ext_controls controls;
    memset(&control, 0, sizeof(control));
    memset(&controls, 0, sizeof(controls));

    control.id = control_id;
    control.value = desired;
    controls.ctrl_class = V4L2_CTRL_ID2CLASS(control_id);
    controls.count = 1;
    controls.controls = &control;

    if (IoctlLocked(VIDIOC_S_EXT_CTRLS, &controls) < 0) {
      HAL_LOGE("S_EXT_CTRLS fails: %s", strerror(errno));
      return -ENODEV;
    }
    result_value = control.value;
  } else {
    v4l2_control control{control_id, desired};
    if (IoctlLocked(VIDIOC_S_CTRL, &control) < 0) {
      HAL_LOGE("S_CTRL fails: %s", strerror(errno));
      return -ENODEV;
    }
    result_value = control.value;
  }

  // If the caller wants to know the result, pass it back.
  if (result != nullptr) {
    *result = result_value;
  }
  return 0;
}

int V4L2Wrapper::GetFormats(std::set<uint32_t>* v4l2_formats) {
  HAL_LOG_ENTER();

  v4l2_fmtdesc format_query;
  memset(&format_query, 0, sizeof(format_query));
  // TODO(b/30000211): multiplanar support.
  format_query.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
  while (IoctlLocked(VIDIOC_ENUM_FMT, &format_query) >= 0) {
    v4l2_formats->insert(format_query.pixelformat);
    ++format_query.index;
  }

  if (errno != EINVAL) {
    HAL_LOGE(
        "ENUM_FMT fails at index %d: %s", format_query.index, strerror(errno));
    return -ENODEV;
  }
  return 0;
}

int V4L2Wrapper::GetFormatFrameSizes(uint32_t v4l2_format,
                                     std::set<std::array<int32_t, 2>>* sizes) {
  v4l2_frmsizeenum size_query;
  memset(&size_query, 0, sizeof(size_query));
  size_query.pixel_format = v4l2_format;
  if (IoctlLocked(VIDIOC_ENUM_FRAMESIZES, &size_query) < 0) {
    HAL_LOGE("ENUM_FRAMESIZES failed: %s", strerror(errno));
    return -ENODEV;
  }
  if (size_query.type == V4L2_FRMSIZE_TYPE_DISCRETE) {
    // Discrete: enumerate all sizes using VIDIOC_ENUM_FRAMESIZES.
    // Assuming that a driver with discrete frame sizes has a reasonable number
    // of them.
    do {
      sizes->insert({{{static_cast<int32_t>(size_query.discrete.width),
                       static_cast<int32_t>(size_query.discrete.height)}}});
      ++size_query.index;
    } while (IoctlLocked(VIDIOC_ENUM_FRAMESIZES, &size_query) >= 0);
    if (errno != EINVAL) {
      HAL_LOGE("ENUM_FRAMESIZES fails at index %d: %s",
               size_query.index,
               strerror(errno));
      return -ENODEV;
    }
  } else {
    // Continuous/Step-wise: based on the stepwise struct returned by the query.
    // Fully listing all possible sizes, with large enough range/small enough
    // step size, may produce far too many potential sizes. Instead, find the
    // closest to a set of standard sizes.
    for (const auto size : kStandardSizes) {
      // Find the closest size, rounding up.
      uint32_t desired_width = size[0];
      uint32_t desired_height = size[1];
      if (desired_width < size_query.stepwise.min_width ||
          desired_height < size_query.stepwise.min_height) {
        HAL_LOGV("Standard size %u x %u is too small for format %d",
                 desired_width,
                 desired_height,
                 v4l2_format);
        continue;
      } else if (desired_width > size_query.stepwise.max_width &&
                 desired_height > size_query.stepwise.max_height) {
        HAL_LOGV("Standard size %u x %u is too big for format %d",
                 desired_width,
                 desired_height,
                 v4l2_format);
        continue;
      }

      // Round up.
      uint32_t width_steps = (desired_width - size_query.stepwise.min_width +
                              size_query.stepwise.step_width - 1) /
                             size_query.stepwise.step_width;
      uint32_t height_steps = (desired_height - size_query.stepwise.min_height +
                               size_query.stepwise.step_height - 1) /
                              size_query.stepwise.step_height;
      sizes->insert(
          {{{static_cast<int32_t>(size_query.stepwise.min_width +
                                  width_steps * size_query.stepwise.step_width),
             static_cast<int32_t>(size_query.stepwise.min_height +
                                  height_steps *
                                      size_query.stepwise.step_height)}}});
    }
  }
  return 0;
}

// Converts a v4l2_fract with units of seconds to an int64_t with units of ns.
inline int64_t FractToNs(const v4l2_fract& fract) {
  return (1000000000LL * fract.numerator) / fract.denominator;
}

int V4L2Wrapper::GetFormatFrameDurationRange(
    uint32_t v4l2_format,
    const std::array<int32_t, 2>& size,
    std::array<int64_t, 2>* duration_range) {
  // Potentially called so many times logging entry is a bad idea.

  v4l2_frmivalenum duration_query;
  memset(&duration_query, 0, sizeof(duration_query));
  duration_query.pixel_format = v4l2_format;
  duration_query.width = size[0];
  duration_query.height = size[1];
  if (IoctlLocked(VIDIOC_ENUM_FRAMEINTERVALS, &duration_query) < 0) {
    HAL_LOGE("ENUM_FRAMEINTERVALS failed: %s", strerror(errno));
    return -ENODEV;
  }

  int64_t min = std::numeric_limits<int64_t>::max();
  int64_t max = std::numeric_limits<int64_t>::min();
  if (duration_query.type == V4L2_FRMSIZE_TYPE_DISCRETE) {
    // Discrete: enumerate all durations using VIDIOC_ENUM_FRAMEINTERVALS.
    do {
      min = std::min(min, FractToNs(duration_query.discrete));
      max = std::max(max, FractToNs(duration_query.discrete));
      ++duration_query.index;
    } while (IoctlLocked(VIDIOC_ENUM_FRAMEINTERVALS, &duration_query) >= 0);
    if (errno != EINVAL) {
      HAL_LOGE("ENUM_FRAMEINTERVALS fails at index %d: %s",
               duration_query.index,
               strerror(errno));
      return -ENODEV;
    }
  } else {
    // Continuous/Step-wise: simply convert the given min and max.
    min = FractToNs(duration_query.stepwise.min);
    max = FractToNs(duration_query.stepwise.max);
  }
  (*duration_range)[0] = min;
  (*duration_range)[1] = max;
  return 0;
}

int V4L2Wrapper::SetFormat(const StreamFormat& desired_format,
                           uint32_t* result_max_buffers) {
  HAL_LOG_ENTER();

  if (format_ && desired_format == *format_) {
    HAL_LOGV("Already in correct format, skipping format setting.");
    *result_max_buffers = buffers_.size();
    return 0;
  }

  // Not in the correct format, set the new one.

  if (format_) {
    // If we had an old format, first request 0 buffers to inform the device
    // we're no longer using any previously "allocated" buffers from the old
    // format. This seems like it shouldn't be necessary for USERPTR memory,
    // and/or should happen from turning the stream off, but the driver
    // complained. May be a driver issue, or may be intended behavior.
    int res = RequestBuffers(0);
    if (res) {
      return res;
    }
  }

  // Set the camera to the new format.
  v4l2_format new_format;
  desired_format.FillFormatRequest(&new_format);
  // TODO(b/29334616): When async, this will need to check if the stream
  // is on, and if so, lock it off while setting format.

  if (IoctlLocked(VIDIOC_S_FMT, &new_format) < 0) {
    HAL_LOGE("S_FMT failed: %s", strerror(errno));
    return -ENODEV;
  }

  // Check that the driver actually set to the requested values.
  if (desired_format != new_format) {
    HAL_LOGE("Device doesn't support desired stream configuration.");
    return -EINVAL;
  }

  // Keep track of our new format.
  format_.reset(new StreamFormat(new_format));

  // Format changed, request new buffers.
  int res = RequestBuffers(1);
  if (res) {
    HAL_LOGE("Requesting buffers for new format failed.");
    return res;
  }
  *result_max_buffers = buffers_.size();
  return 0;
}

int V4L2Wrapper::RequestBuffers(uint32_t num_requested) {
  v4l2_requestbuffers req_buffers;
  memset(&req_buffers, 0, sizeof(req_buffers));
  req_buffers.type = format_->type();
  req_buffers.memory = V4L2_MEMORY_USERPTR;
  req_buffers.count = num_requested;

  int res = IoctlLocked(VIDIOC_REQBUFS, &req_buffers);
  // Calling REQBUFS releases all queued buffers back to the user.
  int gralloc_res = gralloc_->unlockAllBuffers();
  if (res < 0) {
    HAL_LOGE("REQBUFS failed: %s", strerror(errno));
    return -ENODEV;
  }
  if (gralloc_res < 0) {
    HAL_LOGE("Failed to unlock all buffers when setting up new buffers.");
    return gralloc_res;
  }

  // V4L2 will set req_buffers.count to a number of buffers it can handle.
  if (num_requested > 0 && req_buffers.count < 1) {
    HAL_LOGE("REQBUFS claims it can't handle any buffers.");
    return -ENODEV;
  }
  buffers_.resize(req_buffers.count, false);

  return 0;
}

int V4L2Wrapper::EnqueueBuffer(const camera3_stream_buffer_t* camera_buffer,
                               uint32_t* enqueued_index) {
  if (!format_) {
    HAL_LOGE("Stream format must be set before enqueuing buffers.");
    return -ENODEV;
  }

  // Find a free buffer index. Could use some sort of persistent hinting
  // here to improve expected efficiency, but buffers_.size() is expected
  // to be low enough (<10 experimentally) that it's not worth it.
  int index = -1;
  {
    std::lock_guard<std::mutex> guard(buffer_queue_lock_);
    for (int i = 0; i < buffers_.size(); ++i) {
      if (!buffers_[i]) {
        index = i;
        break;
      }
    }
  }
  if (index < 0) {
    // Note: The HAL should be tracking the number of buffers in flight
    // for each stream, and should never overflow the device.
    HAL_LOGE("Cannot enqueue buffer: stream is already full.");
    return -ENODEV;
  }

  // Set up a v4l2 buffer struct.
  v4l2_buffer device_buffer;
  memset(&device_buffer, 0, sizeof(device_buffer));
  device_buffer.type = format_->type();
  device_buffer.index = index;

  // Use QUERYBUF to ensure our buffer/device is in good shape,
  // and fill out remaining fields.
  if (IoctlLocked(VIDIOC_QUERYBUF, &device_buffer) < 0) {
    HAL_LOGE("QUERYBUF fails: %s", strerror(errno));
    return -ENODEV;
  }

  // Lock the buffer for writing (fills in the user pointer field).
  int res =
      gralloc_->lock(camera_buffer, format_->bytes_per_line(), &device_buffer);
  if (res) {
    HAL_LOGE("Gralloc failed to lock buffer.");
    return res;
  }
  if (IoctlLocked(VIDIOC_QBUF, &device_buffer) < 0) {
    HAL_LOGE("QBUF fails: %s", strerror(errno));
    gralloc_->unlock(&device_buffer);
    return -ENODEV;
  }

  // Mark the buffer as in flight.
  std::lock_guard<std::mutex> guard(buffer_queue_lock_);
  buffers_[index] = true;

  if (enqueued_index) {
    *enqueued_index = index;
  }
  return 0;
}

int V4L2Wrapper::DequeueBuffer(uint32_t* dequeued_index) {
  if (!format_) {
    HAL_LOGV(
        "Format not set, so stream can't be on, "
        "so no buffers available for dequeueing");
    return -EAGAIN;
  }

  v4l2_buffer buffer;
  memset(&buffer, 0, sizeof(buffer));
  buffer.type = format_->type();
  buffer.memory = V4L2_MEMORY_USERPTR;
  int res = IoctlLocked(VIDIOC_DQBUF, &buffer);
  if (res) {
    if (errno == EAGAIN) {
      // Expected failure.
      return -EAGAIN;
    } else {
      // Unexpected failure.
      HAL_LOGE("DQBUF fails: %s", strerror(errno));
      return -ENODEV;
    }
  }

  // Mark the buffer as no longer in flight.
  {
    std::lock_guard<std::mutex> guard(buffer_queue_lock_);
    buffers_[buffer.index] = false;
  }

  // Now that we're done painting the buffer, we can unlock it.
  res = gralloc_->unlock(&buffer);
  if (res) {
    HAL_LOGE("Gralloc failed to unlock buffer after dequeueing.");
    return res;
  }

  if (dequeued_index) {
    *dequeued_index = buffer.index;
  }
  return 0;
}

}  // namespace v4l2_camera_hal