| Message ID | 20210513092246.42847-9-jacopo@jmondi.org |
|---|---|
| State | Superseded |
| Delegated to: | Jacopo Mondi |
| Headers | show |
| Series |
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| Related | show |
Hi Jacopo, thank you for the patch. On Thu, May 13, 2021 at 6:22 PM Jacopo Mondi <jacopo@jmondi.org> wrote: > > Implement the flush() camera operation in the CameraDevice class > and make it available to the camera framework by implementing the > operation wrapper in camera_ops.cpp. > > The flush() implementation stops the Camera and the worker thread and > waits for all in-flight requests to be returned. Stopping the Camera > forces all Requests already queued to be returned immediately in error > state. As flush() has to wait until all of them have been returned, make it > wait on a newly introduced condition variable which is notified by the > request completion handler when the queue of pending requests has been > exhausted. > > As flush() can race with processCaptureRequest() protect the requests > queueing by introducing a new CameraState::CameraFlushing state that > processCaptureRequest() inspects before queuing the Request to the > Camera. If flush() has been called while processCaptureRequest() was > executing, return the current Request immediately in error state. > > Signed-off-by: Jacopo Mondi <jacopo@jmondi.org> > --- > src/android/camera_device.cpp | 91 +++++++++++++++++++++++++++++++++-- > src/android/camera_device.h | 9 +++- > src/android/camera_ops.cpp | 8 ++- > 3 files changed, 102 insertions(+), 6 deletions(-) > > diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp > index 7f8c9bd7832d..6d6730a50ec7 100644 > --- a/src/android/camera_device.cpp > +++ b/src/android/camera_device.cpp > @@ -750,16 +750,64 @@ int CameraDevice::open(const hw_module_t *hardwareModule) > > void CameraDevice::close() > { > - streams_.clear(); > + MutexLocker cameraLock(cameraMutex_); > + if (state_ == CameraFlushing) { > + MutexLocker flushLock(flushMutex_); > + flushed_.wait(flushLock, [&] { return state_ != CameraStopped; }); > + camera_->release(); > > + return; > + } > + > + streams_.clear(); > stop(); > > camera_->release(); > } > > +/* > + * Flush is similar to stop() but sets the camera state to 'flushing' and wait > + * until all the in-flight requests have been returned before setting the > + * camera state to stopped. > + * > + * Once flushing is done it unlocks concurrent camera close() calls or new > + * camera configurations. > + */ > +void CameraDevice::flush() > +{ > + { > + MutexLocker cameraLock(cameraMutex_); > + > + if (state_ != CameraRunning) > + return; > + > + worker_.stop(); > + camera_->stop(); > + state_ = CameraFlushing; > + } > + > + /* > + * Now wait for all the in-flight requests to be completed before > + * continuing. Stopping the Camera guarantees that all in-flight > + * requests are completed in error state. > + */ > + { > + MutexLocker requestsLock(requestsMutex_); > + flushing_.wait(requestsLock, [&] { return descriptors_.empty(); }); > + } > + > + /* > + * Unlock close() or configureStreams() that might be waiting for > + * flush to be completed. > + */ > + MutexLocker flushLocker(flushMutex_); I found state_ is touched without cameraMutex_ here and the condition variable of flushed_.wait(). I suspect that flushMutex_ is unnecessary and should be replaced with cameraMutex_. > > + state_ = CameraStopped; > + flushed_.notify_one(); > +} > + > +/* Calls to stop() must be protected by cameraMutex_ being held by the caller. */ > void CameraDevice::stop() > { > - MutexLocker cameraLock(cameraMutex_); > if (state_ == CameraStopped) > return; > > @@ -1652,8 +1700,20 @@ PixelFormat CameraDevice::toPixelFormat(int format) const > */ > int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list) > { > - /* Before any configuration attempt, stop the camera. */ > - stop(); > + { > + /* > + * If a flush is in progress, wait for it to complete and to > + * stop the camera, otherwise before any new configuration > + * attempt we have to stop the camera explictely. > + */ > + MutexLocker cameraLock(cameraMutex_); > + if (state_ == CameraFlushing) { > + MutexLocker flushLock(flushMutex_); > + flushed_.wait(flushLock, [&] { return state_ != CameraStopped; }); > + } else { > + stop(); > + } > + } I wonder if we should hold cameraMutex_ entirely in configureStreams() because we are touching streams_ and camera_, which are also accessed by flush() and stop(). > > > if (stream_list->num_streams == 0) { > LOG(HAL, Error) << "No streams in configuration"; CaptureRequest, which is constructed through Camera3RequestDescriptor. CaptureRequest::queue() calls camera_->queueRequest(). It is necessary to make sure camera_ is valid at that time. It seems to be difficult because it is a different thread and therefore we don't have any idea when it is called. Although I think https://patchwork.libcamera.org/patch/12089 helps our situation. > > @@ -2021,6 +2081,25 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques > if (ret) > return ret; > > + /* > + * Just before queuing the request, make sure flush() has not > + * been called after this function has been executed. In that > + * case, immediately return the request with errors. > + */ > + MutexLocker cameraLock(cameraMutex_); > + if (state_ == CameraFlushing || state_ == CameraStopped) { > + for (camera3_stream_buffer_t &buffer : descriptor.buffers_) { > + buffer.status = CAMERA3_BUFFER_STATUS_ERROR; > + buffer.release_fence = buffer.acquire_fence; > + } > + > + notifyError(descriptor.frameNumber_, > + descriptor.buffers_[0].stream, > + CAMERA3_MSG_ERROR_REQUEST); > + > + return 0; > + } > + > worker_.queueRequest(descriptor.request_.get()); > > { > @@ -2050,6 +2129,10 @@ void CameraDevice::requestComplete(Request *request) > return; > } > > + /* Release flush if all the pending requests have been completed. */ > + if (descriptors_.empty()) > + flushing_.notify_one(); > + The flush() document states flush() should only return when there are no more outstanding buffers or requests left in the HAL. Is it okay that flush() returns before notifyError() and process_capture_result() is called? -Hiro > > node = descriptors_.extract(it); > } > Camera3RequestDescriptor &descriptor = node.mapped(); > diff --git a/src/android/camera_device.h b/src/android/camera_device.h > index ed992ae56d5d..9c55cc2674b7 100644 > --- a/src/android/camera_device.h > +++ b/src/android/camera_device.h > @@ -7,6 +7,7 @@ > #ifndef __ANDROID_CAMERA_DEVICE_H__ > #define __ANDROID_CAMERA_DEVICE_H__ > > +#include <condition_variable> > #include <map> > #include <memory> > #include <mutex> > @@ -42,6 +43,7 @@ public: > > int open(const hw_module_t *hardwareModule); > void close(); > + void flush(); > > unsigned int id() const { return id_; } > camera3_device_t *camera3Device() { return &camera3Device_; } > @@ -92,6 +94,7 @@ private: > enum State { > CameraStopped, > CameraRunning, > + CameraFlushing, > }; > > void stop(); > @@ -124,6 +127,9 @@ private: > libcamera::Mutex cameraMutex_; /* Protects access to the camera state. */ > State state_; > > + libcamera::Mutex flushMutex_; /* Protects the flushed_ condition variable. */ > + std::condition_variable flushed_; > + > std::shared_ptr<libcamera::Camera> camera_; > std::unique_ptr<libcamera::CameraConfiguration> config_; > > @@ -135,8 +141,9 @@ private: > std::map<int, libcamera::PixelFormat> formatsMap_; > std::vector<CameraStream> streams_; > > - libcamera::Mutex requestsMutex_; /* Protects descriptors_. */ > + libcamera::Mutex requestsMutex_; /* Protects descriptors_ and flushing_. */ > std::map<uint64_t, Camera3RequestDescriptor> descriptors_; > + std::condition_variable flushing_; > > std::string maker_; > std::string model_; > diff --git a/src/android/camera_ops.cpp b/src/android/camera_ops.cpp > index 696e80436821..8a3cfa175ff5 100644 > --- a/src/android/camera_ops.cpp > +++ b/src/android/camera_ops.cpp > @@ -66,8 +66,14 @@ static void hal_dev_dump([[maybe_unused]] const struct camera3_device *dev, > { > } > > -static int hal_dev_flush([[maybe_unused]] const struct camera3_device *dev) > +static int hal_dev_flush(const struct camera3_device *dev) > { > + if (!dev) > + return -EINVAL; > + > + CameraDevice *camera = reinterpret_cast<CameraDevice *>(dev->priv); > + camera->flush(); > + > return 0; > } > > -- > 2.31.1 > > _______________________________________________ > libcamera-devel mailing list > libcamera-devel@lists.libcamera.org > https://lists.libcamera.org/listinfo/libcamera-devel
Hi Hiro, On Mon, May 17, 2021 at 02:51:45PM +0900, Hirokazu Honda wrote: > Hi Jacopo, thank you for the patch. > > > > On Thu, May 13, 2021 at 6:22 PM Jacopo Mondi <jacopo@jmondi.org> wrote: > > > > Implement the flush() camera operation in the CameraDevice class > > and make it available to the camera framework by implementing the > > operation wrapper in camera_ops.cpp. > > > > The flush() implementation stops the Camera and the worker thread and > > waits for all in-flight requests to be returned. Stopping the Camera > > forces all Requests already queued to be returned immediately in error > > state. As flush() has to wait until all of them have been returned, make > it > > wait on a newly introduced condition variable which is notified by the > > request completion handler when the queue of pending requests has been > > exhausted. > > > > As flush() can race with processCaptureRequest() protect the requests > > queueing by introducing a new CameraState::CameraFlushing state that > > processCaptureRequest() inspects before queuing the Request to the > > Camera. If flush() has been called while processCaptureRequest() was > > executing, return the current Request immediately in error state. > > > > Signed-off-by: Jacopo Mondi <jacopo@jmondi.org> > > --- > > src/android/camera_device.cpp | 91 +++++++++++++++++++++++++++++++++-- > > src/android/camera_device.h | 9 +++- > > src/android/camera_ops.cpp | 8 ++- > > 3 files changed, 102 insertions(+), 6 deletions(-) > > > > diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp > > index 7f8c9bd7832d..6d6730a50ec7 100644 > > --- a/src/android/camera_device.cpp > > +++ b/src/android/camera_device.cpp > > @@ -750,16 +750,64 @@ int CameraDevice::open(const hw_module_t > *hardwareModule) > > > > void CameraDevice::close() > > { > > - streams_.clear(); > > + MutexLocker cameraLock(cameraMutex_); > > + if (state_ == CameraFlushing) { > > + MutexLocker flushLock(flushMutex_); > > + flushed_.wait(flushLock, [&] { return state_ != > CameraStopped; }); > > + camera_->release(); > > > > + return; > > + } > > + > > + streams_.clear(); > > stop(); > > > > camera_->release(); > > } > > > > +/* > > + * Flush is similar to stop() but sets the camera state to 'flushing' > and wait > > + * until all the in-flight requests have been returned before setting the > > + * camera state to stopped. > > + * > > + * Once flushing is done it unlocks concurrent camera close() calls or > new > > + * camera configurations. > > + */ > > +void CameraDevice::flush() > > +{ > > + { > > + MutexLocker cameraLock(cameraMutex_); > > + > > + if (state_ != CameraRunning) > > + return; > > + > > + worker_.stop(); > > + camera_->stop(); > > + state_ = CameraFlushing; > > + } > > + > > + /* > > + * Now wait for all the in-flight requests to be completed before > > + * continuing. Stopping the Camera guarantees that all in-flight > > + * requests are completed in error state. > > + */ > > + { > > + MutexLocker requestsLock(requestsMutex_); > > + flushing_.wait(requestsLock, [&] { return > descriptors_.empty(); }); > > + } > > + > > + /* > > + * Unlock close() or configureStreams() that might be waiting for > > + * flush to be completed. > > + */ > > + MutexLocker flushLocker(flushMutex_); > > > I found state_ is touched without cameraMutex_ here and the condition > variable of flushed_.wait(). I didn't get the "and the condition variable..." part. However, on the first part, I don't think it's a problem, and that's my reasoning: if we get here the camera state is set to flushing already. Whatever other thread that calls a concurrent close(), configureStreams() or processCaptureRequest() will find the CameraState set to flushing, if flush() gets the CameraMutex_ critical section first. Those threads will see the CameraState as CameraFlushing and will wait on the flushed_ condition variable, until flush() notifies them here below, after having changed the camera state. if close() or configureStreams() gets the CameraMutex_ critical section first they will just stop the camera. When mutex gets in the critical section, it will find the camera is not running anymore, and will simply return. if processCaptureRequest() gets the critical section first, it will queue the request normally. Once flush() enters the critical section it will stop the camera and the request will be completed with errors as usual. > I suspect that flushMutex_ is unnecessary and should be replaced with > cameraMutex_. You might be right.. flushMutex_ usage in close() and configureStreams() can be replaced with cameraMutex_ easily. I'll try this, thanks for the suggestion. > > > > > > + state_ = CameraStopped; > > + flushed_.notify_one(); > > +} > > + > > +/* Calls to stop() must be protected by cameraMutex_ being held by the > caller. */ > > void CameraDevice::stop() > > { > > - MutexLocker cameraLock(cameraMutex_); > > if (state_ == CameraStopped) > > return; > > > > @@ -1652,8 +1700,20 @@ PixelFormat CameraDevice::toPixelFormat(int > format) const > > */ > > int CameraDevice::configureStreams(camera3_stream_configuration_t > *stream_list) > > { > > - /* Before any configuration attempt, stop the camera. */ > > - stop(); > > + { > > + /* > > + * If a flush is in progress, wait for it to complete and > to > > + * stop the camera, otherwise before any new configuration > > + * attempt we have to stop the camera explictely. > > + */ > > + MutexLocker cameraLock(cameraMutex_); > > + if (state_ == CameraFlushing) { > > + MutexLocker flushLock(flushMutex_); > > + flushed_.wait(flushLock, [&] { return state_ != > CameraStopped; }); > > + } else { > > + stop(); > > + } > > + } > > > I wonder if we should hold cameraMutex_ entirely in configureStreams() > because we are touching streams_ and camera_, which are also accessed by > flush() and stop(). > I refrained from accessing streams_ in flush to avoid locking the whole function, which is quite a poor solution as we're back to basically serialize function calls and that's it. Regarding the camera state, the critical section at the beginning makes sure configureStreams() runs with the camera in CameraStopped state, in which case a flush() called during configureStreams() execution will bail out immediately, as there are no requests to flush. OTOH if configureStreams() is called while flush() is executing, it will wait on the flushed_ condition untile flush() has completed and the camera is again in stopped state. > > > > > > if (stream_list->num_streams == 0) { > > LOG(HAL, Error) << "No streams in configuration"; > > > CaptureRequest, which is constructed through Camera3RequestDescriptor. > CaptureRequest::queue() calls camera_->queueRequest(). It is necessary to > make sure camera_ is valid at that time. The request queueing in processCaptureRequest() is performed while helding the CameraMutex_ to prevent a flush to interrupt it. Did I get your comment wrongly ? > It seems to be difficult because it is a different thread and therefore we > don't have any idea when it is called. > Although I think https://patchwork.libcamera.org/patch/12089 helps our > situation. Ah you meant what happens to requests that have not been yet queued on the Camera as they worker is waiting on their fences ? yes, I think stopping the worker_ should return the request immediately. I missed that patch, I'll give it a go. Overall, my understanding is that trying to remove flushMutex_ and use cameraMutex_ in its place should be enough to solve your concerns ? Thanks j > > > > > @@ -2021,6 +2081,25 @@ int > CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques > > if (ret) > > return ret; > > > > + /* > > + * Just before queuing the request, make sure flush() has not > > + * been called after this function has been executed. In that > > + * case, immediately return the request with errors. > > + */ > > + MutexLocker cameraLock(cameraMutex_); > > + if (state_ == CameraFlushing || state_ == CameraStopped) { > > + for (camera3_stream_buffer_t &buffer : > descriptor.buffers_) { > > + buffer.status = CAMERA3_BUFFER_STATUS_ERROR; > > + buffer.release_fence = buffer.acquire_fence; > > + } > > + > > + notifyError(descriptor.frameNumber_, > > + descriptor.buffers_[0].stream, > > + CAMERA3_MSG_ERROR_REQUEST); > > + > > + return 0; > > + } > > + > > worker_.queueRequest(descriptor.request_.get()); > > > > { > > @@ -2050,6 +2129,10 @@ void CameraDevice::requestComplete(Request > *request) > > return; > > } > > > > + /* Release flush if all the pending requests have been > completed. */ > > + if (descriptors_.empty()) > > + flushing_.notify_one(); > > + > > The flush() document states > > flush() should only return when there are no more outstanding buffers or > requests left in the HAL. > > > Is it okay that flush() returns before notifyError() and > process_capture_result() is called? > > -Hiro > > > > > node = descriptors_.extract(it); > > } > > Camera3RequestDescriptor &descriptor = node.mapped(); > > diff --git a/src/android/camera_device.h b/src/android/camera_device.h > > index ed992ae56d5d..9c55cc2674b7 100644 > > --- a/src/android/camera_device.h > > +++ b/src/android/camera_device.h > > @@ -7,6 +7,7 @@ > > #ifndef __ANDROID_CAMERA_DEVICE_H__ > > #define __ANDROID_CAMERA_DEVICE_H__ > > > > +#include <condition_variable> > > #include <map> > > #include <memory> > > #include <mutex> > > @@ -42,6 +43,7 @@ public: > > > > int open(const hw_module_t *hardwareModule); > > void close(); > > + void flush(); > > > > unsigned int id() const { return id_; } > > camera3_device_t *camera3Device() { return &camera3Device_; } > > @@ -92,6 +94,7 @@ private: > > enum State { > > CameraStopped, > > CameraRunning, > > + CameraFlushing, > > }; > > > > void stop(); > > @@ -124,6 +127,9 @@ private: > > libcamera::Mutex cameraMutex_; /* Protects access to the camera > state. */ > > State state_; > > > > + libcamera::Mutex flushMutex_; /* Protects the flushed_ condition > variable. */ > > + std::condition_variable flushed_; > > + > > std::shared_ptr<libcamera::Camera> camera_; > > std::unique_ptr<libcamera::CameraConfiguration> config_; > > > > @@ -135,8 +141,9 @@ private: > > std::map<int, libcamera::PixelFormat> formatsMap_; > > std::vector<CameraStream> streams_; > > > > - libcamera::Mutex requestsMutex_; /* Protects descriptors_. */ > > + libcamera::Mutex requestsMutex_; /* Protects descriptors_ and > flushing_. */ > > std::map<uint64_t, Camera3RequestDescriptor> descriptors_; > > + std::condition_variable flushing_; > > > > std::string maker_; > > std::string model_; > > diff --git a/src/android/camera_ops.cpp b/src/android/camera_ops.cpp > > index 696e80436821..8a3cfa175ff5 100644 > > --- a/src/android/camera_ops.cpp > > +++ b/src/android/camera_ops.cpp > > @@ -66,8 +66,14 @@ static void hal_dev_dump([[maybe_unused]] const struct > camera3_device *dev, > > { > > } > > > > -static int hal_dev_flush([[maybe_unused]] const struct camera3_device > *dev) > > +static int hal_dev_flush(const struct camera3_device *dev) > > { > > + if (!dev) > > + return -EINVAL; > > + > > + CameraDevice *camera = reinterpret_cast<CameraDevice > *>(dev->priv); > > + camera->flush(); > > + > > return 0; > > } > > > > -- > > 2.31.1 > > > > _______________________________________________ > > libcamera-devel mailing list > > libcamera-devel@lists.libcamera.org > > https://lists.libcamera.org/listinfo/libcamera-devel
Hi Jacopo, On Thu, May 20, 2021 at 5:29 PM Jacopo Mondi <jacopo@jmondi.org> wrote: > Hi Hiro, > > On Mon, May 17, 2021 at 02:51:45PM +0900, Hirokazu Honda wrote: > > Hi Jacopo, thank you for the patch. > > > > > > > > On Thu, May 13, 2021 at 6:22 PM Jacopo Mondi <jacopo@jmondi.org> wrote: > > > > > > Implement the flush() camera operation in the CameraDevice class > > > and make it available to the camera framework by implementing the > > > operation wrapper in camera_ops.cpp. > > > > > > The flush() implementation stops the Camera and the worker thread and > > > waits for all in-flight requests to be returned. Stopping the Camera > > > forces all Requests already queued to be returned immediately in error > > > state. As flush() has to wait until all of them have been returned, > make > > it > > > wait on a newly introduced condition variable which is notified by the > > > request completion handler when the queue of pending requests has been > > > exhausted. > > > > > > As flush() can race with processCaptureRequest() protect the requests > > > queueing by introducing a new CameraState::CameraFlushing state that > > > processCaptureRequest() inspects before queuing the Request to the > > > Camera. If flush() has been called while processCaptureRequest() was > > > executing, return the current Request immediately in error state. > > > > > > Signed-off-by: Jacopo Mondi <jacopo@jmondi.org> > > > --- > > > src/android/camera_device.cpp | 91 +++++++++++++++++++++++++++++++++-- > > > src/android/camera_device.h | 9 +++- > > > src/android/camera_ops.cpp | 8 ++- > > > 3 files changed, 102 insertions(+), 6 deletions(-) > > > > > > diff --git a/src/android/camera_device.cpp > b/src/android/camera_device.cpp > > > index 7f8c9bd7832d..6d6730a50ec7 100644 > > > --- a/src/android/camera_device.cpp > > > +++ b/src/android/camera_device.cpp > > > @@ -750,16 +750,64 @@ int CameraDevice::open(const hw_module_t > > *hardwareModule) > > > > > > void CameraDevice::close() > > > { > > > - streams_.clear(); > > > + MutexLocker cameraLock(cameraMutex_); > > > + if (state_ == CameraFlushing) { > > > + MutexLocker flushLock(flushMutex_); > > > + flushed_.wait(flushLock, [&] { return state_ != > > CameraStopped; }); > > > + camera_->release(); > > > > > > + return; > > > + } > > > + > > > + streams_.clear(); > > > stop(); > > > > > > camera_->release(); > > > } > > > > > > +/* > > > + * Flush is similar to stop() but sets the camera state to 'flushing' > > and wait > > > + * until all the in-flight requests have been returned before setting > the > > > + * camera state to stopped. > > > + * > > > + * Once flushing is done it unlocks concurrent camera close() calls or > > new > > > + * camera configurations. > > > + */ > > > +void CameraDevice::flush() > > > +{ > > > + { > > > + MutexLocker cameraLock(cameraMutex_); > > > + > > > + if (state_ != CameraRunning) > > > + return; > > > + > > > + worker_.stop(); > > > + camera_->stop(); > > > + state_ = CameraFlushing; > > > + } > > > + > > > + /* > > > + * Now wait for all the in-flight requests to be completed > before > > > + * continuing. Stopping the Camera guarantees that all > in-flight > > > + * requests are completed in error state. > > > + */ > > > + { > > > + MutexLocker requestsLock(requestsMutex_); > > > + flushing_.wait(requestsLock, [&] { return > > descriptors_.empty(); }); > > > + } > > > + > > > + /* > > > + * Unlock close() or configureStreams() that might be waiting > for > > > + * flush to be completed. > > > + */ > > > + MutexLocker flushLocker(flushMutex_); > > > > > > I found state_ is touched without cameraMutex_ here and the condition > > variable of flushed_.wait(). > > I didn't get the "and the condition variable..." part. > > Probably I should have said condition block. I meant flushed_.wait(..., { HERE }) in configureStreams() by "the condition variable" . + MutexLocker flushLock(flushMutex_); + flushed_.wait(flushLock, [&] { return state_ != CameraStopped; }); The part is protected by cameraMutex_ but I consider more, by that, flushMutex_ is useless. > However, on the first part, I don't think it's a problem, and that's > my reasoning: if we get here the camera state is set to flushing > already. > > Whatever other thread that calls a concurrent close(), > configureStreams() or processCaptureRequest() will find the > CameraState set to flushing, if flush() gets the CameraMutex_ critical > section first. Those threads will see the CameraState as > CameraFlushing and will wait on the flushed_ condition variable, until > flush() notifies them here below, after having changed the camera state. > > if close() or configureStreams() gets the CameraMutex_ critical > section first they will just stop the camera. When mutex gets in the > critical section, it will find the camera is not running anymore, and > will simply return. > > if processCaptureRequest() gets the critical section first, it will > queue the request normally. Once flush() enters the critical section > it will stop the camera and the request will be completed with errors > as usual. > > I got it. You're right. But I would not do so as it breaks the rule that state_ is protected by cameraMutex_. > > I suspect that flushMutex_ is unnecessary and should be replaced with > > cameraMutex_. > > You might be right.. flushMutex_ usage in close() and > configureStreams() can be replaced with cameraMutex_ easily. > I'll try this, thanks for the suggestion. > > > > > > > > > > > + state_ = CameraStopped; > > > + flushed_.notify_one(); > > > +} > > > + > > > +/* Calls to stop() must be protected by cameraMutex_ being held by the > > caller. */ > > > void CameraDevice::stop() > > > { > > > - MutexLocker cameraLock(cameraMutex_); > If I looked the flow correctly, the state is never Flushing here, so let's add ASSERT(state_ != CameraFlushing); > > > if (state_ == CameraStopped) > > > return; > > > > > > @@ -1652,8 +1700,20 @@ PixelFormat CameraDevice::toPixelFormat(int > > format) const > > > */ > > > int CameraDevice::configureStreams(camera3_stream_configuration_t > > *stream_list) > > > { > > > - /* Before any configuration attempt, stop the camera. */ > > > - stop(); > > > + { > > > + /* > > > + * If a flush is in progress, wait for it to complete > and > > to > > > + * stop the camera, otherwise before any new > configuration > > > + * attempt we have to stop the camera explictely. > > > + */ > > > + MutexLocker cameraLock(cameraMutex_); > > > + if (state_ == CameraFlushing) { > > > + MutexLocker flushLock(flushMutex_); > > > + flushed_.wait(flushLock, [&] { return state_ != > > CameraStopped; }); > > > + } else { > > > + stop(); > > > + } > > > + } > > > > > > I wonder if we should hold cameraMutex_ entirely in configureStreams() > > because we are touching streams_ and camera_, which are also accessed by > > flush() and stop(). > > > > I refrained from accessing streams_ in flush to avoid locking the > whole function, which is quite a poor solution as we're back to > basically serialize function calls and that's it. Regarding the camera > state, the critical section at the beginning makes sure > configureStreams() runs with the camera in CameraStopped state, in > which case a flush() called during configureStreams() execution will > bail out immediately, as there are no requests to flush. OTOH if > configureStreams() is called while flush() is executing, it will wait > on the flushed_ condition untile flush() has completed and the camera > is again in stopped state. > > > This sounds correct. > > > > > > > > > if (stream_list->num_streams == 0) { > > > LOG(HAL, Error) << "No streams in configuration"; > > > > > > CaptureRequest, which is constructed through Camera3RequestDescriptor. > > CaptureRequest::queue() calls camera_->queueRequest(). It is necessary to > > make sure camera_ is valid at that time. > > The request queueing in processCaptureRequest() is performed while > helding the CameraMutex_ to prevent a flush to interrupt it. Did I get > your comment wrongly ? > > It seems to be difficult because it is a different thread and therefore we > > don't have any idea when it is called. > > Although I think https://patchwork.libcamera.org/patch/12089 helps our > > situation. > > Ah you meant what happens to requests that have not been yet queued on > the Camera as they worker is waiting on their fences ? yes, I think > stopping the worker_ should return the request immediately. I missed > that patch, I'll give it a go. > > Yes. CameraWorker::queueRequest() is worker_.InvokeMethod(&processRequest, ConnectionTypeQueued, request); It is not guaranteed that Camera::queueRequest() is called by the end of processCaptureRequest(). > Overall, my understanding is that trying to remove flushMutex_ and use > cameraMutex_ in its place should be enough to solve your concerns ? > > Yeah, I think the action item is only that. Thanks, -Hiro > Thanks > j > > > > > > > > > @@ -2021,6 +2081,25 @@ int > > CameraDevice::processCaptureRequest(camera3_capture_request_t > *camera3Reques > > > if (ret) > > > return ret; > > > > > > + /* > > > + * Just before queuing the request, make sure flush() has not > > > + * been called after this function has been executed. In that > > > + * case, immediately return the request with errors. > > > + */ > > > + MutexLocker cameraLock(cameraMutex_); > > > + if (state_ == CameraFlushing || state_ == CameraStopped) { > > > + for (camera3_stream_buffer_t &buffer : > > descriptor.buffers_) { > > > + buffer.status = CAMERA3_BUFFER_STATUS_ERROR; > > > + buffer.release_fence = buffer.acquire_fence; > > > + } > > > + > > > + notifyError(descriptor.frameNumber_, > > > + descriptor.buffers_[0].stream, > > > + CAMERA3_MSG_ERROR_REQUEST); > > > + > > > + return 0; > > > + } > > > + > > > worker_.queueRequest(descriptor.request_.get()); > > > > > > { > > > @@ -2050,6 +2129,10 @@ void CameraDevice::requestComplete(Request > > *request) > > > return; > > > } > > > > > > + /* Release flush if all the pending requests have been > > completed. */ > > > + if (descriptors_.empty()) > > > + flushing_.notify_one(); > > > + > > > > The flush() document states > > > > flush() should only return when there are no more outstanding buffers or > > requests left in the HAL. > > > > > > Is it okay that flush() returns before notifyError() and > > process_capture_result() is called? > > > > -Hiro > > > > > > > > node = descriptors_.extract(it); > > > } > > > Camera3RequestDescriptor &descriptor = node.mapped(); > > > diff --git a/src/android/camera_device.h b/src/android/camera_device.h > > > index ed992ae56d5d..9c55cc2674b7 100644 > > > --- a/src/android/camera_device.h > > > +++ b/src/android/camera_device.h > > > @@ -7,6 +7,7 @@ > > > #ifndef __ANDROID_CAMERA_DEVICE_H__ > > > #define __ANDROID_CAMERA_DEVICE_H__ > > > > > > +#include <condition_variable> > > > #include <map> > > > #include <memory> > > > #include <mutex> > > > @@ -42,6 +43,7 @@ public: > > > > > > int open(const hw_module_t *hardwareModule); > > > void close(); > > > + void flush(); > > > > > > unsigned int id() const { return id_; } > > > camera3_device_t *camera3Device() { return &camera3Device_; } > > > @@ -92,6 +94,7 @@ private: > > > enum State { > > > CameraStopped, > > > CameraRunning, > > > + CameraFlushing, > > > }; > > > > > > void stop(); > > > @@ -124,6 +127,9 @@ private: > > > libcamera::Mutex cameraMutex_; /* Protects access to the camera > > state. */ > > > State state_; > > > > > > + libcamera::Mutex flushMutex_; /* Protects the flushed_ > condition > > variable. */ > > > + std::condition_variable flushed_; > > > + > > > std::shared_ptr<libcamera::Camera> camera_; > > > std::unique_ptr<libcamera::CameraConfiguration> config_; > > > > > > @@ -135,8 +141,9 @@ private: > > > std::map<int, libcamera::PixelFormat> formatsMap_; > > > std::vector<CameraStream> streams_; > > > > > > - libcamera::Mutex requestsMutex_; /* Protects descriptors_. */ > > > + libcamera::Mutex requestsMutex_; /* Protects descriptors_ and > > flushing_. */ > > > std::map<uint64_t, Camera3RequestDescriptor> descriptors_; > > > + std::condition_variable flushing_; > > > > > > std::string maker_; > > > std::string model_; > > > diff --git a/src/android/camera_ops.cpp b/src/android/camera_ops.cpp > > > index 696e80436821..8a3cfa175ff5 100644 > > > --- a/src/android/camera_ops.cpp > > > +++ b/src/android/camera_ops.cpp > > > @@ -66,8 +66,14 @@ static void hal_dev_dump([[maybe_unused]] const > struct > > camera3_device *dev, > > > { > > > } > > > > > > -static int hal_dev_flush([[maybe_unused]] const struct camera3_device > > *dev) > > > +static int hal_dev_flush(const struct camera3_device *dev) > > > { > > > + if (!dev) > > > + return -EINVAL; > > > + > > > + CameraDevice *camera = reinterpret_cast<CameraDevice > > *>(dev->priv); > > > + camera->flush(); > > > + > > > return 0; > > > } > > > > > > -- > > > 2.31.1 > > > > > > _______________________________________________ > > > libcamera-devel mailing list > > > libcamera-devel@lists.libcamera.org > > > https://lists.libcamera.org/listinfo/libcamera-devel >
diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp index 7f8c9bd7832d..6d6730a50ec7 100644 --- a/src/android/camera_device.cpp +++ b/src/android/camera_device.cpp @@ -750,16 +750,64 @@ int CameraDevice::open(const hw_module_t *hardwareModule) void CameraDevice::close() { - streams_.clear(); + MutexLocker cameraLock(cameraMutex_); + if (state_ == CameraFlushing) { + MutexLocker flushLock(flushMutex_); + flushed_.wait(flushLock, [&] { return state_ != CameraStopped; }); + camera_->release(); + return; + } + + streams_.clear(); stop(); camera_->release(); } +/* + * Flush is similar to stop() but sets the camera state to 'flushing' and wait + * until all the in-flight requests have been returned before setting the + * camera state to stopped. + * + * Once flushing is done it unlocks concurrent camera close() calls or new + * camera configurations. + */ +void CameraDevice::flush() +{ + { + MutexLocker cameraLock(cameraMutex_); + + if (state_ != CameraRunning) + return; + + worker_.stop(); + camera_->stop(); + state_ = CameraFlushing; + } + + /* + * Now wait for all the in-flight requests to be completed before + * continuing. Stopping the Camera guarantees that all in-flight + * requests are completed in error state. + */ + { + MutexLocker requestsLock(requestsMutex_); + flushing_.wait(requestsLock, [&] { return descriptors_.empty(); }); + } + + /* + * Unlock close() or configureStreams() that might be waiting for + * flush to be completed. + */ + MutexLocker flushLocker(flushMutex_); + state_ = CameraStopped; + flushed_.notify_one(); +} + +/* Calls to stop() must be protected by cameraMutex_ being held by the caller. */ void CameraDevice::stop() { - MutexLocker cameraLock(cameraMutex_); if (state_ == CameraStopped) return; @@ -1652,8 +1700,20 @@ PixelFormat CameraDevice::toPixelFormat(int format) const */ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list) { - /* Before any configuration attempt, stop the camera. */ - stop(); + { + /* + * If a flush is in progress, wait for it to complete and to + * stop the camera, otherwise before any new configuration + * attempt we have to stop the camera explictely. + */ + MutexLocker cameraLock(cameraMutex_); + if (state_ == CameraFlushing) { + MutexLocker flushLock(flushMutex_); + flushed_.wait(flushLock, [&] { return state_ != CameraStopped; }); + } else { + stop(); + } + } if (stream_list->num_streams == 0) { LOG(HAL, Error) << "No streams in configuration"; @@ -2021,6 +2081,25 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques if (ret) return ret; + /* + * Just before queuing the request, make sure flush() has not + * been called after this function has been executed. In that + * case, immediately return the request with errors. + */ + MutexLocker cameraLock(cameraMutex_); + if (state_ == CameraFlushing || state_ == CameraStopped) { + for (camera3_stream_buffer_t &buffer : descriptor.buffers_) { + buffer.status = CAMERA3_BUFFER_STATUS_ERROR; + buffer.release_fence = buffer.acquire_fence; + } + + notifyError(descriptor.frameNumber_, + descriptor.buffers_[0].stream, + CAMERA3_MSG_ERROR_REQUEST); + + return 0; + } + worker_.queueRequest(descriptor.request_.get()); { @@ -2050,6 +2129,10 @@ void CameraDevice::requestComplete(Request *request) return; } + /* Release flush if all the pending requests have been completed. */ + if (descriptors_.empty()) + flushing_.notify_one(); + node = descriptors_.extract(it); } Camera3RequestDescriptor &descriptor = node.mapped(); diff --git a/src/android/camera_device.h b/src/android/camera_device.h index ed992ae56d5d..9c55cc2674b7 100644 --- a/src/android/camera_device.h +++ b/src/android/camera_device.h @@ -7,6 +7,7 @@ #ifndef __ANDROID_CAMERA_DEVICE_H__ #define __ANDROID_CAMERA_DEVICE_H__ +#include <condition_variable> #include <map> #include <memory> #include <mutex> @@ -42,6 +43,7 @@ public: int open(const hw_module_t *hardwareModule); void close(); + void flush(); unsigned int id() const { return id_; } camera3_device_t *camera3Device() { return &camera3Device_; } @@ -92,6 +94,7 @@ private: enum State { CameraStopped, CameraRunning, + CameraFlushing, }; void stop(); @@ -124,6 +127,9 @@ private: libcamera::Mutex cameraMutex_; /* Protects access to the camera state. */ State state_; + libcamera::Mutex flushMutex_; /* Protects the flushed_ condition variable. */ + std::condition_variable flushed_; + std::shared_ptr<libcamera::Camera> camera_; std::unique_ptr<libcamera::CameraConfiguration> config_; @@ -135,8 +141,9 @@ private: std::map<int, libcamera::PixelFormat> formatsMap_; std::vector<CameraStream> streams_; - libcamera::Mutex requestsMutex_; /* Protects descriptors_. */ + libcamera::Mutex requestsMutex_; /* Protects descriptors_ and flushing_. */ std::map<uint64_t, Camera3RequestDescriptor> descriptors_; + std::condition_variable flushing_; std::string maker_; std::string model_; diff --git a/src/android/camera_ops.cpp b/src/android/camera_ops.cpp index 696e80436821..8a3cfa175ff5 100644 --- a/src/android/camera_ops.cpp +++ b/src/android/camera_ops.cpp @@ -66,8 +66,14 @@ static void hal_dev_dump([[maybe_unused]] const struct camera3_device *dev, { } -static int hal_dev_flush([[maybe_unused]] const struct camera3_device *dev) +static int hal_dev_flush(const struct camera3_device *dev) { + if (!dev) + return -EINVAL; + + CameraDevice *camera = reinterpret_cast<CameraDevice *>(dev->priv); + camera->flush(); + return 0; }
Implement the flush() camera operation in the CameraDevice class and make it available to the camera framework by implementing the operation wrapper in camera_ops.cpp. The flush() implementation stops the Camera and the worker thread and waits for all in-flight requests to be returned. Stopping the Camera forces all Requests already queued to be returned immediately in error state. As flush() has to wait until all of them have been returned, make it wait on a newly introduced condition variable which is notified by the request completion handler when the queue of pending requests has been exhausted. As flush() can race with processCaptureRequest() protect the requests queueing by introducing a new CameraState::CameraFlushing state that processCaptureRequest() inspects before queuing the Request to the Camera. If flush() has been called while processCaptureRequest() was executing, return the current Request immediately in error state. Signed-off-by: Jacopo Mondi <jacopo@jmondi.org> --- src/android/camera_device.cpp | 91 +++++++++++++++++++++++++++++++++-- src/android/camera_device.h | 9 +++- src/android/camera_ops.cpp | 8 ++- 3 files changed, 102 insertions(+), 6 deletions(-)