[libcamera-devel] [PATCH v2 3/4] android: camera_hal_manager: Support camera hotplug
Niklas Söderlund
niklas.soderlund at ragnatech.se
Thu Aug 13 13:44:18 CEST 2020
Hi Umang,
Thanks for your work.
On 2020-08-10 12:04:14 +0000, Umang Jain wrote:
> Extend the support for camera hotplug from libcamera's CameraManager
> to CameraHalManager. Use camera module callbacks to let the framework
> know about the hotplug events and change the status of cameras being
> being hotplugged or unplugged via camera_device_status_change().
>
> Introduce a map camerasMap_ which book-keeps all cameras seen in the
> past by the CameraHalManager. If the camera is seen for the first time,
> a new id is assigned to it. If the camera has been seen before by the
> manager, it's old id is reused. IDs for internal cameras start with
> '0' and for external cameras, they start with '1000'. Note, for the
> current implementation, we assume all UVC cameras are external cameras.
I wonder if keeping the cache of previously seen cameras or if we should
not just treat any hot-plugged camera as a new one? I can't think of any
benefit of preserving the same numerical ID between two plug events,
while I can think of quiet a few cons.
- It's confusing when debugging as un-plugging and then replugging the
same camera will result in logs where the numerical ID is the same for
both. This may even result in things working by "chance" is it reuses
an already known numerical ID.
- Looking at the code plugging a UVC camera in a different USB port will
generate a different Camera::id() result and then be treated as a new
camera vs plugging it in the same port and it then being treatad as a
new camera.
- The logic in this patch is more complex due to it both having to deal
with known and new cameras.
What is the benefit of this cache that I'm missing?
>
> CameraDevice is now a shared object and cameras_ vector stores shared
> pointers to CameraDevice. This is done in order to introduce reference
> counting for CameraDevice objects - especially to handle hot-unplug
> events. Both camerasMap_ and cameras_ are protected by a mutex.
>
> Signed-off-by: Umang Jain <email at uajain.com>
> ---
> src/android/camera_device.cpp | 15 +++
> src/android/camera_device.h | 8 +-
> src/android/camera_hal_manager.cpp | 153 ++++++++++++++++++++++++-----
> src/android/camera_hal_manager.h | 15 ++-
> 4 files changed, 166 insertions(+), 25 deletions(-)
>
> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> index d918350..a79bb69 100644
> --- a/src/android/camera_device.cpp
> +++ b/src/android/camera_device.cpp
> @@ -233,6 +233,21 @@ CameraDevice::~CameraDevice()
> delete it.second;
> }
>
> +std::shared_ptr<CameraDevice> CameraDevice::create(unsigned int id,
> + const std::shared_ptr<Camera> &cam)
> +{
> + struct Deleter : std::default_delete<CameraDevice> {
> + void operator()(CameraDevice *camera)
> + {
> + delete camera;
> + }
> + };
> +
> + CameraDevice *camera = new CameraDevice(id, cam);
> +
> + return std::shared_ptr<CameraDevice>(camera, Deleter());
> +}
As Kieran points out I think this should be added in a separate as this
one is quiet large and therefore hard to review.
> +
> /*
> * Initialize the camera static information.
> * This method is called before the camera device is opened.
> diff --git a/src/android/camera_device.h b/src/android/camera_device.h
> index 7be9e11..7f9e010 100644
> --- a/src/android/camera_device.h
> +++ b/src/android/camera_device.h
> @@ -47,8 +47,8 @@ struct CameraStream {
> class CameraDevice : protected libcamera::Loggable
> {
> public:
> - CameraDevice(unsigned int id, const std::shared_ptr<libcamera::Camera> &camera);
> - ~CameraDevice();
> + static std::shared_ptr<CameraDevice> create(unsigned int id,
> + const std::shared_ptr<libcamera::Camera> &cam);
>
> int initialize();
>
> @@ -57,6 +57,7 @@ public:
>
> unsigned int id() const { return id_; }
> camera3_device_t *camera3Device() { return &camera3Device_; }
> + const libcamera::Camera *getCamera() { return camera_.get(); };
Same here this can be done in a separate commit. Also I think this could
be named camera() instead of getCamera()
>
> int facing() const { return facing_; }
> int orientation() const { return orientation_; }
> @@ -72,6 +73,9 @@ protected:
> std::string logPrefix() const override;
>
> private:
> + CameraDevice(unsigned int id, const std::shared_ptr<libcamera::Camera> &camera);
> + ~CameraDevice();
> +
> struct Camera3RequestDescriptor {
> Camera3RequestDescriptor(unsigned int frameNumber,
> unsigned int numBuffers);
> diff --git a/src/android/camera_hal_manager.cpp b/src/android/camera_hal_manager.cpp
> index 3d6d2b4..fdde2c0 100644
> --- a/src/android/camera_hal_manager.cpp
> +++ b/src/android/camera_hal_manager.cpp
> @@ -8,6 +8,7 @@
> #include "camera_hal_manager.h"
>
> #include <libcamera/camera.h>
> +#include <libcamera/property_ids.h>
>
> #include "libcamera/internal/log.h"
>
> @@ -35,6 +36,7 @@ CameraHalManager::CameraHalManager()
> CameraHalManager::~CameraHalManager()
> {
> cameras_.clear();
> + camerasMap_.clear();
>
> if (cameraManager_) {
> cameraManager_->stop();
> @@ -47,6 +49,13 @@ int CameraHalManager::init()
> {
> cameraManager_ = new CameraManager();
>
> + /* Support camera hotplug. */
> + cameraManager_->cameraAdded.connect(this, &CameraHalManager::cameraAdded);
> + cameraManager_->cameraRemoved.connect(this, &CameraHalManager::cameraRemoved);
> +
> + cameraCounter_ = 0;
> + externalCameraCounter_ = 1000;
> +
> int ret = cameraManager_->start();
> if (ret) {
> LOG(HAL, Error) << "Failed to start camera manager: "
> @@ -56,35 +65,25 @@ int CameraHalManager::init()
> return ret;
> }
>
> - /*
> - * For each Camera registered in the system, a CameraDevice
> - * gets created here to wraps a libcamera Camera instance.
> - *
> - * \todo Support camera hotplug.
> - */
> - unsigned int index = 0;
> - for (auto &cam : cameraManager_->cameras()) {
> - CameraDevice *camera = new CameraDevice(index, cam);
> - ret = camera->initialize();
> - if (ret)
> - continue;
> -
> - cameras_.emplace_back(camera);
> - ++index;
> - }
> -
> return 0;
> }
>
> CameraDevice *CameraHalManager::open(unsigned int id,
> const hw_module_t *hardwareModule)
> {
> - if (id >= numCameras()) {
> + MutexLocker locker(mutex_);
> +
> + auto iter = std::find_if(cameras_.begin(), cameras_.end(),
> + [id](std::shared_ptr<CameraDevice> &cam) {
> + return cam->id() == id;
> + });
> + if (iter == cameras_.end()) {
I think you should break this (and the similar ones below) into private
helpers instead if implementing the logic in-place
CameraHalManager::cameraFromAndroidId(..);
CameraHalManager::androidIdFromCamera(..);
> LOG(HAL, Error) << "Invalid camera id '" << id << "'";
> return nullptr;
> }
>
> - CameraDevice *camera = cameras_[id].get();
> + CameraDevice *camera = iter->get();
> +
> if (camera->open(hardwareModule))
> return nullptr;
>
> @@ -93,9 +92,91 @@ CameraDevice *CameraHalManager::open(unsigned int id,
> return camera;
> }
>
> +void CameraHalManager::cameraAdded(std::shared_ptr<Camera> cam)
> +{
> + unsigned int id;
> + bool isCameraExternal = false;
> + bool isCameraNew = false;
> +
> + MutexLocker locker(mutex_);
> +
> + /* Each camera is assigned a unique integer id when it is seen for the
> + * first time. If the camera has been seen before, the id is reused and
> + * the camera is marked as CAMERA_DEVICE_STATUS_PRESENT subsequently.
> + *
> + * ID starts from '0' for internal cameras and '1000' for external cameras.
> + */
> + auto iter = camerasMap_.find(cam->id());
> + if (iter != camerasMap_.end()) {
> + id = iter->second;
> + } else {
> + isCameraNew = true;
> +
> + /*
> + * Now check if this is an external camera and assign
> + * its id accordingly.
> + */
> + const ControlList &properties = cam->properties();
> + if (properties.contains(properties::Location) &&
> + properties.get(properties::Location) &
> + properties::CameraLocationExternal) {
> + isCameraExternal = true;
> + id = externalCameraCounter_;
> + } else {
> + id = cameraCounter_;
> + }
As I understand it the information the HAL wants is whether or not the
camera can be hot-plugged (id >= 1000) or nor (id < 1000)?
If so I wonder if using the camera location as a judgment of the camera
is hot-plugged or not is the way to go here? Imagine a device where the
camera is permanently attached (not hot-unpluggable) but not fixated in
a location. I'm thinking cameras mounted at the end of instruments
(medical instruments, hand held tools) or robotics (mounted at the arm
of a welding robot). I would imagine those cameras would be marked as
located externally but they would not really be hot-pluggable.
I understand we have no other way to report or detect this at the moment
and I'm not pushing hard for this to be solved as part of this series if
it's not easy. But I think a bigger comment here is needed explaining
that the HAL wants to know if a camera is hot-pluggable or not and does
not really care if it's located internally or externally. I also think a
\todo should be added so it's not forgotten.
> + }
> +
> + /*
> + * For each Camera registered in the system, a CameraDevice
> + * gets created here to wraps a libcamera Camera instance.
> + */
> + std::shared_ptr<CameraDevice> camera = CameraDevice::create(id, std::move(cam));
> + int ret = camera->initialize();
> + if (ret) {
> + LOG(HAL, Error) << "Failed to initialize camera: " << cam->id();
> + return;
> + }
> +
> + if (isCameraNew) {
> + camerasMap_.emplace(cam->id(), id);
> +
> + if (isCameraExternal)
> + externalCameraCounter_++;
> + else
> + cameraCounter_++;
> + }
> +
> + cameras_.emplace_back(std::move(camera));
> +
> + if (callbacks_)
> + callbacks_->camera_device_status_change(callbacks_, id,
> + CAMERA_DEVICE_STATUS_PRESENT);
> + LOG(HAL, Debug) << "Camera ID: " << id << " added successfully.";
> +}
> +
> +void CameraHalManager::cameraRemoved(std::shared_ptr<Camera> cam)
> +{
> + MutexLocker locker(mutex_);
> +
> + auto iter = std::find_if(cameras_.begin(), cameras_.end(),
> + [cam](std::shared_ptr<CameraDevice> &camera) {
> + return cam.get() == camera->getCamera();
> + });
> + if (iter == cameras_.end())
> + return;
> +
> + unsigned int id = (*iter)->id();
> + callbacks_->camera_device_status_change(callbacks_, id,
> + CAMERA_DEVICE_STATUS_NOT_PRESENT);
> + cameras_.erase(iter);
> +
> + LOG(HAL, Debug) << "Camera ID: " << id << " removed successfully.";
> +}
> +
> unsigned int CameraHalManager::numCameras() const
> {
> - return cameraManager_->cameras().size();
> + return cameraCounter_;
> }
>
> int CameraHalManager::getCameraInfo(unsigned int id, struct camera_info *info)
> @@ -103,12 +184,18 @@ int CameraHalManager::getCameraInfo(unsigned int id, struct camera_info *info)
> if (!info)
> return -EINVAL;
>
> - if (id >= numCameras()) {
> + MutexLocker locker(mutex_);
> +
> + auto iter = std::find_if(cameras_.begin(), cameras_.end(),
> + [id](std::shared_ptr<CameraDevice> &cam) {
> + return cam->id() == id;
> + });
> + if (iter == cameras_.end()) {
> LOG(HAL, Error) << "Invalid camera id '" << id << "'";
> return -EINVAL;
> }
>
> - CameraDevice *camera = cameras_[id].get();
> + CameraDevice *camera = iter->get();
>
> info->facing = camera->facing();
> info->orientation = camera->orientation();
> @@ -124,4 +211,26 @@ int CameraHalManager::getCameraInfo(unsigned int id, struct camera_info *info)
> void CameraHalManager::setCallbacks(const camera_module_callbacks_t *callbacks)
> {
> callbacks_ = callbacks;
> +
> + MutexLocker locker(mutex_);
> + /*
> + * Few cameras might have been hotplugged before setting callbacks_ here.
> + * We need to mark CAMERA_DEVICE_STATUS_PRESENT for them explicitly.
> + * This hold only for external cameras, as internal cameras are assumed to
> + * be present at module load time, by the framework.
> + */
> + for (auto &cam : cameraManager_->cameras()) {
> + auto iter = camerasMap_.find(cam->id());
> + if (iter == camerasMap_.end())
> + continue;
> +
> + unsigned int id = iter->second;
> + const ControlList &properties = cam->properties();
> + if (properties.contains(properties::Location) &&
> + properties.get(properties::Location) &
> + properties::CameraLocationExternal) {
> + callbacks_->camera_device_status_change(callbacks_, id,
> + CAMERA_DEVICE_STATUS_PRESENT);
> + }
> + }
> }
> diff --git a/src/android/camera_hal_manager.h b/src/android/camera_hal_manager.h
> index a582f04..7c481d4 100644
> --- a/src/android/camera_hal_manager.h
> +++ b/src/android/camera_hal_manager.h
> @@ -7,6 +7,8 @@
> #ifndef __ANDROID_CAMERA_MANAGER_H__
> #define __ANDROID_CAMERA_MANAGER_H__
>
> +#include <map>
> +#include <mutex>
> #include <stddef.h>
> #include <vector>
>
> @@ -18,6 +20,9 @@
>
> class CameraDevice;
>
> +using Mutex = std::mutex;
> +using MutexLocker = std::unique_lock<std::mutex>;
> +
> class CameraHalManager
> {
> public:
> @@ -33,10 +38,18 @@ public:
> void setCallbacks(const camera_module_callbacks_t *callbacks);
>
> private:
> + void cameraAdded(std::shared_ptr<libcamera::Camera> cam);
> + void cameraRemoved(std::shared_ptr<libcamera::Camera> cam);
> +
> libcamera::CameraManager *cameraManager_;
>
> const camera_module_callbacks_t *callbacks_;
> - std::vector<std::unique_ptr<CameraDevice>> cameras_;
> + std::vector<std::shared_ptr<CameraDevice>> cameras_;
> + std::map<std::string, unsigned int> camerasMap_;
If each hot-plugged camera where treated as a new camera cameras_ and
camerasMap_ could be merged to a
std::map<unsigned int, std::shared_ptr<CameraDevice>> cameras_;
Which would eliminate the possibility of them going out-of-sync.
> + Mutex mutex_;
> +
> + unsigned int externalCameraCounter_;
> + unsigned int cameraCounter_;
> };
>
> #endif /* __ANDROID_CAMERA_MANAGER_H__ */
> --
> 2.26.2
>
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> libcamera-devel at lists.libcamera.org
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--
Regards,
Niklas Söderlund
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