[libcamera-devel] [PATCH v4 0/8] Implement flush() camera operation

[Jacopo Mondi]

To get to a successfull implementation of flush() a bit of preparatory work is
required as currently Requests that fails to queue to the pipeline handler are
not returned to the application. Add Request::cancel() and call it in the
PipelineHandler base class when calling queueRequestDevice() fails to allow
application to keep track of the queued requests.

On top of that, prepare the CameraDevice to support flush with a few clean-up
patches, then implement the operation.

No regression detected when running CTS in LIMITED mode.

Tested with cros_camera_test:

   # cros_camera_test --gtest_filter="Camera3FrameTest/Camera3FlushRequestsTest*"
   [==========] 12 tests from 1 test suite ran. (1380 ms total)
   [  PASSED  ] 12 tests.

All patches reviewed but the last!

Thanks
  j

v3->v4:
 - [1/8] Set stream to nullptr when the error code does not require it
 - [1/8] Drop a useless error message
 - [2/8] Take in style suggestion from Laurent
 - [4/8] Use enum class CameraDevice::State
 - [8/8] Reimplement flush assuming it only races with processCaptureRequest

v2->v3:
 - Request::cancel():
   - Add tracepoint in request.tp
   - Emitt Camera::bufferCompleted signal for each cancelled buffer
   - Do not complete the Request

 - PipelineHandler
   - Do not emit Camera::bufferCompleted as Request::cancel() does so
   - Do not complete the request immediately but call
     PipelineHandler::completeRequest()

 - Flush
   - Use CameraMutex_ in place of FlushMutex_ to wait on the flushed_ condition
     as suggested by Hiro. This guarantees that any access to the camera state
     is protected by the same mutex and code is simplified.
   - Assert that stop() does not get called while flushing as suggested by Hiro.

v1->v2:
 - The majority of patches in the series have not been changed if not for
   collecting tags. However 8/8 which implement the actual flush() has been
   changed to address Hiro's comment about protecting close() and
   configureStreams() from being concurrently run with flush().

   - 8/8:
     - Introduce a new flushed_ condition variable to be used by close() and
       configureStreams() to be unlocked when flushing has terminated.

- The patches that introduce Request::cancel() has pending discussion with
  Hiro and Niklas. As they impact the libcamera API I'll wait for Laurent to
  chime-in.

Jacopo Mondi (8):
  android: Rework request completion notification
  libcamera: request: Add Request::cancel()
  libcamera: pipeline_handler: Cancel Request on queueing failure
  android: camera_device: Replace running_ with CameraState
  android: Replace scoped_lock<> with libcamera::MutexLocker
  android: Guard access to the camera state
  android: Rename CameraDevice::mutex_
  android: Implement flush() camera operation

 .../libcamera/internal/tracepoints/request.tp |   8 +
 include/libcamera/request.h                   |   1 +
 src/android/camera_device.cpp                 | 236 +++++++++++++-----
 src/android/camera_device.h                   |  18 +-
 src/android/camera_ops.cpp                    |   8 +-
 src/libcamera/pipeline_handler.cpp            |   8 +-
 src/libcamera/request.cpp                     |  23 ++
 7 files changed, 228 insertions(+), 74 deletions(-)

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2.31.1