blob: ea1f0a9f7a32fa47adecf00b0c17e9d72e3729c3 [file] [log] [blame]
// Copyright 2017 The Fuchsia 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 <fidl/>
#include <lib/async-loop/cpp/loop.h>
#include <lib/async-loop/default.h>
#include <lib/async/cpp/task.h>
#include <lib/async/default.h>
#include <lib/fidl/cpp/binding.h>
#include <lib/fit/function.h>
#include <lib/fzl/vmo-pool.h>
#include <lib/zx/vmo.h>
#include <memory>
#include <ddktl/device.h>
#include <ddktl/protocol/empty-protocol.h>
#include <fbl/mutex.h>
#include <usb/usb.h>
#include "src/camera/drivers/usb_video/usb_state.h"
#include "src/camera/drivers/usb_video/video_frame.h"
namespace camera::usb_video {
class UsbVideoStream;
// Stores a usb_request_t in memory.
// An async_task is used here instead of a asyc::TaskMethod to that the task can
// keep track of the request to be handled.
class RequestTask : public async_task {
RequestTask(usb_request_t* req, UsbVideoStream* context);
static void AsyncTaskHandler(async_dispatcher_t* dispatcher, async_task_t* task,
zx_status_t status);
usb_request_t* req() { return &req_; }
usb_request_t req_;
UsbVideoStream* context_;
std::vector<uint8_t> data_;
// UsbVideoStream State Machine:
// [DISCONNECTED] ------<GetChannel()>---------> [STOPPED]
// /|\ / |
// | --------<stream.OnClose()> |
// <control.OnClose>--/-------------- / |
// | / \ | \|/
// [STREAMING] <--Start()--- [READY] <--- <CreateStream()>
// All states ------> Unbind() ----> [UNBOUND]
// State transition table:
// Cells marked with Error will return an error if attempted, but
// will not result in a state transition.
// Cells marked with N/A are not possible due to lack of channel to
// make the call.
// Initial State
// GetChannel | STOPPED | Error! | Error! | Error!
// CreateStream | N/A | READY | Error! | Error!
// Start | N/A | N/A | STREAMING | Error!
// Stop | N/A | N/A | Error! | READY
// stream close | N/A | N/A | STOPPED | STOPPED
// The Unbind action closes all channels, and disallows any further state transitions.
// The state can be determined as follows:
// if (unbind txn set) -> UNBOUND
// if (!control channel) -> DISCONNECTED
// elif (!stream channel) -> STOPPED
// elif (!is_streaming_) -> READY
// else -> STREAMING
// This device does not allow multiple simultaneous control connections via GetChannel,
// nor does it allow multiple streaming connections via CreateStream.
// Any failure in communication over the control or stream channel will result in that channel
// being closed, along with the state transitions that closure implies.
// Calling Stop() may not stop the usb device from streaming video frames, but
// It will cause this device to stop notifying the client of new frames via OnFrameAvailable.
// When Start() is called after calling Stop(), OnFrameAvailable will be called when the next
// available frame is filled, so the capture time may have occurred before Start() was called.
// The stream_token eventpair passed with CreateStream will be ignored by this device,
// although it will retain ownership of the token until the stream is shut down following
// closure of the stream channel.
// Unless specified otherwise, all methods of this class are assumed to be called
// on the single threaded dispatcher owned by this class.
class UsbVideoStream;
using UsbVideoStreamBase =
::ddk::Device<UsbVideoStream, ::ddk::Unbindable,
class UsbVideoStream : public UsbVideoStreamBase,
public fuchsia::camera::Control,
public fuchsia::camera::Stream,
public ::ddk::EmptyProtocol<ZX_PROTOCOL_CAMERA> {
// Constructor is assumed to be called only through Bind, or suitable testing rig.
// This method will not be called on the fidl_dispatch_loop_.
UsbVideoStream(zx_device_t* parent, usb_protocol_t usb, StreamingSetting settings);
// DDK device implementation
// DdkUnbind posts an async task on the fidl_dispatch_loop_.
void DdkUnbind(::ddk::UnbindTxn txn) __TA_EXCLUDES(lock_) {
fbl::AutoLock lock(&lock_);
unbind_txn_ = std::move(txn);
// Release is guaranteed to only be called after receiving the async reply
// to DdkUnbind.
// This method will not be called on the fidl_dispatch_loop_.
void DdkRelease() { delete this; }
~UsbVideoStream() override = default;
// This method will not be called on the fidl_dispatch_loop_.
static zx_status_t Bind(void* ctx, zx_device_t* device);
// Fuchsia Hardware Camera FIDL implementation.
// These three calls may not be called on the fidl_dispatch_loop_.
void GetChannel2(GetChannel2RequestView request, GetChannel2Completer::Sync& completer) override {
// Call not supported
void GetChannel(GetChannelRequestView request, GetChannelCompleter::Sync& completer) override
void GetDebugChannel(GetDebugChannelRequestView request,
GetDebugChannelCompleter::Sync& completer) override {
// --------------------------------------------------------------
// Fidl Implementation for fuchsia::camera::Control
// --------------------------------------------------------------
// Get the available format types for this device
void GetFormats(uint32_t index, GetFormatsCallback callback) override;
// Get the vendor and product information for this device
void GetDeviceInfo(GetDeviceInfoCallback callback) override;
// Configures a video stream.
// The BufferCollectionInfo contains the desired image format as well as the
// vmo-backed buffers that are used to transfer the video frames.
// The |stream_token| will be closed by the driver when the stream is fully
// stopped after the stream channel is closed. Otherwise, it is ignored.
void CreateStream(fuchsia::sysmem::BufferCollectionInfo buffer_collection,
fuchsia::camera::FrameRate frame_rate,
fidl::InterfaceRequest<fuchsia::camera::Stream> stream,
zx::eventpair stream_token) override __TA_EXCLUDES(lock_);
// --------------------------------------------------------------
// Fidl Implementation for fuchsia::camera::Stream
// --------------------------------------------------------------
// Starts the streaming of frames.
void Start() override { CloseStreamOnError(SetStreaming(true), "start"); }
// Stops the streaming of frames.
void Stop() override { CloseStreamOnError(SetStreaming(false), "stop"); }
// Unlocks the specified frame, allowing the driver to reuse the memory.
void ReleaseFrame(uint32_t buffer_index) override {
CloseStreamOnError(FrameRelease(buffer_index), "release frame");
// Sent by the driver to the client when a frame is available for
// processing, or an error occurred.
void OnFrameAvailable(const fuchsia::camera::FrameAvailableEvent& frame) {;
// --------------------------------------------------------------
// Internal functions for interacting with streams
// --------------------------------------------------------------
// Finds a video configuration that matches the format of the buffer collection,
// then maps the buffers given. If a different configuration was previously used,
// it is discarded.
zx_status_t CreateStream(fuchsia::sysmem::BufferCollectionInfo buffer_collection,
fuchsia::camera::FrameRate frame_rate);
// Starts and stops the stream. Retains the configuration when stopping so
// the stream can be re-started.
zx_status_t SetStreaming(bool stream);
// Called when the stream channel is closed.
// We assume this happens in the same dispatcher as any calls to CreateStream
void OnStreamingShutdown() {
current_frame_ = nullptr;
frame_number_ = 0;
is_streaming_ = false;
zx_status_t FrameRelease(uint32_t buffer_id);
// Shuts down the stream and unbinds the stream interface
void CloseStreamOnError(zx_status_t status, const char* call);
// How the driver gets image data from the usb stack.
// Multiple requests will complete per frame.
// The usb thread calls PostRequestCompleteTask, which posts a task to the
// fidl_dispatch_loop_, which is then handled by HandleRequest, which calls
// RequestComplete and deals with the task bookkeeping.
void RequestComplete(usb_request_t* req);
void PostRequestCompleteTask(usb_request_t* req);
void HandleRequest(RequestTask* task);
friend void RequestTask::AsyncTaskHandler(async_dispatcher_t*, async_task_t*, zx_status_t);
// Handles unbinding the streams to prepare for the driver to be removed.
// Only called on the the fidl_dispatch_loop_.
void HandleUnbind(async_dispatcher_t* dispatcher, async::TaskBase* task, zx_status_t status);
// Helper function called only by RequestComplete. Ensures that current_frame_
// exists, and is backed by a buffer if one is available.
void CheckCurrentFrame();
// Threading concerns:
// There are 3 dispatchers that may call into this class.
// 1) Driver Host, which may call:
// -> Unbind/Remove
// -> GetChannel
// 2) Our dispatch loop, which may call
// -> All control and stream channel calls
// 3) The banjo interface, which may call
// -> PostRequestCompleteTask
// To handle conflicts with DdkUnbind and GetChannel, DdkUnbind posts a task
// to the fidl_dispatch_loop_ to handle unbinding.
// GetChannel only accesses the control binding and the unbind reply transaction.
// The async task, the unbind reply transaction and the control binding
// are all guarded by a lock to prevent concurrent access:
fbl::Mutex lock_;
async::TaskMethod<UsbVideoStream, &UsbVideoStream::HandleUnbind> unbind_task_ __TA_GUARDED(lock_);
std::optional<::ddk::UnbindTxn> unbind_txn_ __TA_GUARDED(lock_) = std::nullopt;
fidl::Binding<Control> control_binding_ __TA_GUARDED(lock_);
// To avoid issues with the latter two threads, calls to PostRequestCompleteTask
// are limited to posting a task to be run on the dispatch loop.
// This limits potential collisions between the two threads to the req_list_,
// which is guarded by the req_list_lock_.
fbl::Mutex req_list_lock_;
std::deque<RequestTask> req_list_ __TA_GUARDED(req_list_lock_);
// The other variables are only accessed by methods dispatched by the fidl_dispatch_loop_.
// current_frame_, frame_number_, buffers_ and is_streaming_ are only valid in the
// STREAMING and READY states.
// Current video frame we are populating
std::unique_ptr<VideoFrame> current_frame_;
uint32_t frame_number_ = 0; // used for log messages.
fzl::VmoPool buffers_;
// Used for the Start and Stop function. Start and Stop simply enable/disable
// the driver to call OnFrameAvailable
bool is_streaming_ = false;
UsbState usb_state_;
// Loop used to run the FIDL server
std::unique_ptr<async::Loop> fidl_dispatch_loop_;
zx::eventpair stream_token_;
fidl::Binding<Stream> stream_binding_;
} // namespace camera::usb_video