[{"id":24520,"web_url":"https://patchwork.libcamera.org/comment/24520/","msgid":"<166014406801.15821.18006622305930030211@Monstersaurus>","date":"2022-08-10T15:07:48","subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Hi Laurent,\n\nQuoting Laurent Pinchart (2022-07-21 22:03:51)\n> libcamera implements a pipeline handler locking mechanism based on\n> advisory locks on media devices, to prevent concurrent access to cameras\n> from the same pipeline handler from different processes (this only works\n> between multiple libcamera instances, as other processes won't use\n> advisory locks on media devices).\n> \n> A side effect of the implementation prevents multiple cameras created by\n> the same pipeline handler from being used concurrently. Fix this by\n> turning the PipelineHandler lock() and unlock() functions into acquire()\n> and release(), with a use count to replace the boolean lock flag. The\n> Camera class is updated accordingly.\n> \n> Signed-off-by: Laurent Pinchart \n> ---\n> This may help addressing the problem reported in \"[RFC PATCH] qcam: Fix\n> IPU3 camera switching\".\n\nThis does indeed fix things for me on IPU3 testing with qcam.\nIt however seemed to introduce a regression in CTS (which perhaps\nHarvey's patches will then resolve)\n\nHowever, I think we'll hear from David that this would benefit the RPi\nplatform already...\n\n\nReviewed-by: Kieran Bingham \n\n> ---\n> include/libcamera/internal/camera.h | 1 +\n> include/libcamera/internal/pipeline_handler.h | 8 ++-\n> src/libcamera/camera.cpp | 12 +++-\n> src/libcamera/pipeline_handler.cpp | 63 ++++++++++++-------\n> 4 files changed, 55 insertions(+), 29 deletions(-)\n> \n> diff --git a/include/libcamera/internal/camera.h b/include/libcamera/internal/camera.h\n> index 597426a6f9d2..38dd94ff8156 100644\n> --- a/include/libcamera/internal/camera.h\n> +++ b/include/libcamera/internal/camera.h\n> @@ -50,6 +50,7 @@ private:\n> CameraRunning,\n> };\n> \n> + bool isAcquired() const;\n> bool isRunning() const;\n> int isAccessAllowed(State state, bool allowDisconnected = false,\n> const char *from = __builtin_FUNCTION()) const;\n> diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h\n> index c3e4c2587ecd..20f1cbb07fea 100644\n> --- a/include/libcamera/internal/pipeline_handler.h\n> +++ b/include/libcamera/internal/pipeline_handler.h\n> @@ -45,8 +45,8 @@ public:\n> MediaDevice *acquireMediaDevice(DeviceEnumerator *enumerator,\n> const DeviceMatch &dm);\n> \n> - bool lock();\n> - void unlock();\n> + bool acquire();\n> + void release();\n> \n> virtual CameraConfiguration *generateConfiguration(Camera *camera,\n> const StreamRoles &roles) = 0;\n> @@ -77,6 +77,8 @@ protected:\n> CameraManager *manager_;\n> \n> private:\n> + void unlockMediaDevices();\n> +\n> void mediaDeviceDisconnected(MediaDevice *media);\n> virtual void disconnect();\n> \n> @@ -91,7 +93,7 @@ private:\n> const char *name_;\n> \n> Mutex lock_;\n> - bool lockOwner_ LIBCAMERA_TSA_GUARDED_BY(lock_); /* *Not* ownership of lock_ */\n> + unsigned int useCount_ LIBCAMERA_TSA_GUARDED_BY(lock_);\n> \n> friend class PipelineHandlerFactory;\n> };\n> diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp\n> index 2a8ef60e3862..9ce32db1ac78 100644\n> --- a/src/libcamera/camera.cpp\n> +++ b/src/libcamera/camera.cpp\n> @@ -508,6 +508,11 @@ static const char *const camera_state_names[] = {\n> \"Running\",\n> };\n> \n> +bool Camera::Private::isAcquired() const\n> +{\n> + return state_.load(std::memory_order_acquire) == CameraRunning;\n> +}\n> +\n> bool Camera::Private::isRunning() const\n> {\n> return state_.load(std::memory_order_acquire) == CameraRunning;\n> @@ -811,7 +816,7 @@ int Camera::exportFrameBuffers(Stream *stream,\n> * not blocking, if the device has already been acquired (by the same or another\n> * process) the -EBUSY error code is returned.\n> *\n> - * Acquiring a camera will limit usage of any other camera(s) provided by the\n> + * Acquiring a camera may limit usage of any other camera(s) provided by the\n> * same pipeline handler to the same instance of libcamera. The limit is in\n> * effect until all cameras from the pipeline handler are released. Other\n> * instances of libcamera can still list and examine the cameras but will fail\n> @@ -839,7 +844,7 @@ int Camera::acquire()\n> if (ret < 0)\n> return ret == -EACCES ? -EBUSY : ret;\n> \n> - if (!d->pipe_->lock()) {\n> + if (!d->pipe_->acquire()) {\n> LOG(Camera, Info)\n> << \"Pipeline handler in use by another process\";\n> return -EBUSY;\n> @@ -873,7 +878,8 @@ int Camera::release()\n> if (ret < 0)\n> return ret == -EACCES ? -EBUSY : ret;\n> \n> - d->pipe_->unlock();\n> + if (d->isAcquired())\n> + d->pipe_->release();\n> \n> d->setState(Private::CameraAvailable);\n> \n> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> index 675405330f45..7d2d00ef45e6 100644\n> --- a/src/libcamera/pipeline_handler.cpp\n> +++ b/src/libcamera/pipeline_handler.cpp\n> @@ -68,7 +68,7 @@ LOG_DEFINE_CATEGORY(Pipeline)\n> * respective factories.\n> */\n> PipelineHandler::PipelineHandler(CameraManager *manager)\n> - : manager_(manager), lockOwner_(false)\n> + : manager_(manager), useCount_(0)\n> {\n> }\n> \n> @@ -143,58 +143,75 @@ MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,\n> }\n> \n> /**\n> - * \\brief Lock all media devices acquired by the pipeline\n> + * \\brief Acquire exclusive access to the pipeline handler for the process\n> *\n> - * This function shall not be called from pipeline handler implementation, as\n> - * the Camera class handles locking directly.\n> + * This function locks all the media devices used by the pipeline to ensure\n> + * that no other process can access them concurrently.\n> + *\n> + * Access to a pipeline handler may be acquired recursively from within the\n> + * same process. Every successful acquire() call shall be matched with a\n> + * release() call. This allows concurrent access to the same pipeline handler\n> + * from different cameras within the same process.\n> + *\n> + * Pipeline handlers shall not call this function directly as the Camera class\n> + * handles access internally.\n> *\n> * \\context This function is \\threadsafe.\n> *\n> - * \\return True if the devices could be locked, false otherwise\n> - * \\sa unlock()\n> - * \\sa MediaDevice::lock()\n> + * \\return True if the pipeline handler was acquired, false if another process\n> + * has already acquired it\n> + * \\sa release()\n> */\n> -bool PipelineHandler::lock()\n> +bool PipelineHandler::acquire()\n> {\n> MutexLocker locker(lock_);\n> \n> - /* Do not allow nested locking in the same libcamera instance. */\n> - if (lockOwner_)\n> - return false;\n> + if (useCount_) {\n> + ++useCount_;\n> + return true;\n> + }\n> \n> for (std::shared_ptr &media : mediaDevices_) {\n> if (!media->lock()) {\n> - unlock();\n> + unlockMediaDevices();\n> return false;\n> }\n> }\n> \n> - lockOwner_ = true;\n> -\n> + ++useCount_;\n> return true;\n> }\n> \n> /**\n> - * \\brief Unlock all media devices acquired by the pipeline\n> + * \\brief Release exclusive access to the pipeline handler\n> *\n> - * This function shall not be called from pipeline handler implementation, as\n> - * the Camera class handles locking directly.\n> + * This function releases access to the pipeline handler previously acquired by\n> + * a call to acquire(). Every release() call shall match a previous successful\n> + * acquire() call. Calling this function on a pipeline handler that hasn't been\n> + * acquired results in undefined behaviour.\n> + *\n> + * Pipeline handlers shall not call this function directly as the Camera class\n> + * handles access internally.\n> *\n> * \\context This function is \\threadsafe.\n> *\n> - * \\sa lock()\n> + * \\sa acquire()\n> */\n> -void PipelineHandler::unlock()\n> +void PipelineHandler::release()\n> {\n> MutexLocker locker(lock_);\n> \n> - if (!lockOwner_)\n> - return;\n> + ASSERT(useCount_);\n> \n> + unlockMediaDevices();\n> +\n> + --useCount_;\n> +}\n> +\n> +void PipelineHandler::unlockMediaDevices()\n> +{\n> for (std::shared_ptr &media : mediaDevices_)\n> media->unlock();\n> -\n> - lockOwner_ = false;\n> }\n> \n> /**\n> \n> base-commit: d4eee094e684806dbdb54fbe1bc02c9c590aa7f4\n> -- \n> Regards,\n> \n> Laurent Pinchart\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id E9F3EC3272\n\tfor ;\n\tWed, 10 Aug 2022 15:07:51 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 54AFC6332B;\n\tWed, 10 Aug 2022 17:07:51 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 8BF11600EA\n\tfor ;\n\tWed, 10 Aug 2022 17:07:50 +0200 (CEST)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net [86.31.172.11])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 202603F1;\n\tWed, 10 Aug 2022 17:07:50 +0200 (CEST)"],"DKIM-Signature":["v=1; a=rsa-sha256; c=relaxed/simple; d=libcamera.org;\n\ts=mail; t=1660144071;\n\tbh=Oq1LyQeqi1FFVznQrPFgdnw+SFV/wBw1ZeCEVf8on8Q=;\n\th=In-Reply-To:References:To:Date:Subject:List-Id:List-Unsubscribe:\n\tList-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:\n\tFrom;\n\tb=uh3prCVzW6+dWp3YgE6HpXwr/uB4YAbhTwPjX191EzwwlyJ43Xv9kwl1q1BZkfIy6\n\tMDN1LYqwClqi0Ejv1EPQMo6fc8fq173Kk/kfFckAcax7LPL+7f4KEz63yAYMgX+zJD\n\tqyr2J/Ni1pRoes/s31N0a/R0onYDOUvDXQXyOtfwnT9NEpH7adKYYfEPBWpeM8QcLY\n\tQmANsIeOBPeXhfu0ussqkIoTWvPC9LFF34Y7v6WZiHcmjePWhO8nSohZwhrvuZxF7X\n\tbZGUmBT5oCGQvV3G2rxFLzmH85bL2INuKd8qYTOh5bAqCobX/GCXLKzrlSzmiggU9O\n\t9kOsxiN0P+iug==","v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1660144070;\n\tbh=Oq1LyQeqi1FFVznQrPFgdnw+SFV/wBw1ZeCEVf8on8Q=;\n\th=In-Reply-To:References:Subject:From:To:Cc:Date:From;\n\tb=JRbNKH1eWVXusvdZsLVy0sZ6ILdpedFvdDtdVJr9i5kZbAFEGhopXOL7YqZrxEdhn\n\t08yKXcRsTlH1XVBj6oU7ALCbsWnPfBbRTT8nT4A++xXr/2f37mqVuaZJqMkslRmPu9\n\tu3yLVg/agkvlpfLcxEUmcShtu6QEWklplmR1N3pc="],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"JRbNKH1e\"; dkim-atps=neutral","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20220721210351.1908-1-laurent.pinchart@ideasonboard.com>","References":"<20220721210351.1908-1-laurent.pinchart@ideasonboard.com>","To":"Laurent Pinchart ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Wed, 10 Aug 2022 16:07:48 +0100","Message-ID":"<166014406801.15821.18006622305930030211@Monstersaurus>","User-Agent":"alot/0.10","Subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","From":"Kieran Bingham via libcamera-devel\n\t","Reply-To":"Kieran Bingham ","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":24521,"web_url":"https://patchwork.libcamera.org/comment/24521/","msgid":"","date":"2022-08-10T15:24:55","subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","submitter":{"id":42,"url":"https://patchwork.libcamera.org/api/people/42/","name":"David Plowman","email":"david.plowman@raspberrypi.com"},"content":"Hi Kieran, Laurent\n\nOn Wed, 10 Aug 2022 at 16:07, Kieran Bingham\n wrote:\n>\n> Hi Laurent,\n>\n> Quoting Laurent Pinchart (2022-07-21 22:03:51)\n> > libcamera implements a pipeline handler locking mechanism based on\n> > advisory locks on media devices, to prevent concurrent access to cameras\n> > from the same pipeline handler from different processes (this only works\n> > between multiple libcamera instances, as other processes won't use\n> > advisory locks on media devices).\n> >\n> > A side effect of the implementation prevents multiple cameras created by\n> > the same pipeline handler from being used concurrently. Fix this by\n> > turning the PipelineHandler lock() and unlock() functions into acquire()\n> > and release(), with a use count to replace the boolean lock flag. The\n> > Camera class is updated accordingly.\n> >\n> > Signed-off-by: Laurent Pinchart \n> > ---\n> > This may help addressing the problem reported in \"[RFC PATCH] qcam: Fix\n> > IPU3 camera switching\".\n>\n> This does indeed fix things for me on IPU3 testing with qcam.\n> It however seemed to introduce a regression in CTS (which perhaps\n> Harvey's patches will then resolve)\n>\n> However, I think we'll hear from David that this would benefit the RPi\n> platform already...\n\nYes, this does fix something for me\n(https://github.com/raspberrypi/picamera2/issues/229), so I'd be very\nhappy to see it merged! In my case the real problem was that lock()\ncalls unlock() when it fails, and unlock() tries to grab the mutex\nthat lock() already took. But I can certainly add this for this patch:\n\nTested-by: David Plowman \n\nThanks!\n\nDavid\n\n>\n>\n> Reviewed-by: Kieran Bingham \n>\n> > ---\n> > include/libcamera/internal/camera.h | 1 +\n> > include/libcamera/internal/pipeline_handler.h | 8 ++-\n> > src/libcamera/camera.cpp | 12 +++-\n> > src/libcamera/pipeline_handler.cpp | 63 ++++++++++++-------\n> > 4 files changed, 55 insertions(+), 29 deletions(-)\n> >\n> > diff --git a/include/libcamera/internal/camera.h b/include/libcamera/internal/camera.h\n> > index 597426a6f9d2..38dd94ff8156 100644\n> > --- a/include/libcamera/internal/camera.h\n> > +++ b/include/libcamera/internal/camera.h\n> > @@ -50,6 +50,7 @@ private:\n> > CameraRunning,\n> > };\n> >\n> > + bool isAcquired() const;\n> > bool isRunning() const;\n> > int isAccessAllowed(State state, bool allowDisconnected = false,\n> > const char *from = __builtin_FUNCTION()) const;\n> > diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h\n> > index c3e4c2587ecd..20f1cbb07fea 100644\n> > --- a/include/libcamera/internal/pipeline_handler.h\n> > +++ b/include/libcamera/internal/pipeline_handler.h\n> > @@ -45,8 +45,8 @@ public:\n> > MediaDevice *acquireMediaDevice(DeviceEnumerator *enumerator,\n> > const DeviceMatch &dm);\n> >\n> > - bool lock();\n> > - void unlock();\n> > + bool acquire();\n> > + void release();\n> >\n> > virtual CameraConfiguration *generateConfiguration(Camera *camera,\n> > const StreamRoles &roles) = 0;\n> > @@ -77,6 +77,8 @@ protected:\n> > CameraManager *manager_;\n> >\n> > private:\n> > + void unlockMediaDevices();\n> > +\n> > void mediaDeviceDisconnected(MediaDevice *media);\n> > virtual void disconnect();\n> >\n> > @@ -91,7 +93,7 @@ private:\n> > const char *name_;\n> >\n> > Mutex lock_;\n> > - bool lockOwner_ LIBCAMERA_TSA_GUARDED_BY(lock_); /* *Not* ownership of lock_ */\n> > + unsigned int useCount_ LIBCAMERA_TSA_GUARDED_BY(lock_);\n> >\n> > friend class PipelineHandlerFactory;\n> > };\n> > diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp\n> > index 2a8ef60e3862..9ce32db1ac78 100644\n> > --- a/src/libcamera/camera.cpp\n> > +++ b/src/libcamera/camera.cpp\n> > @@ -508,6 +508,11 @@ static const char *const camera_state_names[] = {\n> > \"Running\",\n> > };\n> >\n> > +bool Camera::Private::isAcquired() const\n> > +{\n> > + return state_.load(std::memory_order_acquire) == CameraRunning;\n> > +}\n> > +\n> > bool Camera::Private::isRunning() const\n> > {\n> > return state_.load(std::memory_order_acquire) == CameraRunning;\n> > @@ -811,7 +816,7 @@ int Camera::exportFrameBuffers(Stream *stream,\n> > * not blocking, if the device has already been acquired (by the same or another\n> > * process) the -EBUSY error code is returned.\n> > *\n> > - * Acquiring a camera will limit usage of any other camera(s) provided by the\n> > + * Acquiring a camera may limit usage of any other camera(s) provided by the\n> > * same pipeline handler to the same instance of libcamera. The limit is in\n> > * effect until all cameras from the pipeline handler are released. Other\n> > * instances of libcamera can still list and examine the cameras but will fail\n> > @@ -839,7 +844,7 @@ int Camera::acquire()\n> > if (ret < 0)\n> > return ret == -EACCES ? -EBUSY : ret;\n> >\n> > - if (!d->pipe_->lock()) {\n> > + if (!d->pipe_->acquire()) {\n> > LOG(Camera, Info)\n> > << \"Pipeline handler in use by another process\";\n> > return -EBUSY;\n> > @@ -873,7 +878,8 @@ int Camera::release()\n> > if (ret < 0)\n> > return ret == -EACCES ? -EBUSY : ret;\n> >\n> > - d->pipe_->unlock();\n> > + if (d->isAcquired())\n> > + d->pipe_->release();\n> >\n> > d->setState(Private::CameraAvailable);\n> >\n> > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> > index 675405330f45..7d2d00ef45e6 100644\n> > --- a/src/libcamera/pipeline_handler.cpp\n> > +++ b/src/libcamera/pipeline_handler.cpp\n> > @@ -68,7 +68,7 @@ LOG_DEFINE_CATEGORY(Pipeline)\n> > * respective factories.\n> > */\n> > PipelineHandler::PipelineHandler(CameraManager *manager)\n> > - : manager_(manager), lockOwner_(false)\n> > + : manager_(manager), useCount_(0)\n> > {\n> > }\n> >\n> > @@ -143,58 +143,75 @@ MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,\n> > }\n> >\n> > /**\n> > - * \\brief Lock all media devices acquired by the pipeline\n> > + * \\brief Acquire exclusive access to the pipeline handler for the process\n> > *\n> > - * This function shall not be called from pipeline handler implementation, as\n> > - * the Camera class handles locking directly.\n> > + * This function locks all the media devices used by the pipeline to ensure\n> > + * that no other process can access them concurrently.\n> > + *\n> > + * Access to a pipeline handler may be acquired recursively from within the\n> > + * same process. Every successful acquire() call shall be matched with a\n> > + * release() call. This allows concurrent access to the same pipeline handler\n> > + * from different cameras within the same process.\n> > + *\n> > + * Pipeline handlers shall not call this function directly as the Camera class\n> > + * handles access internally.\n> > *\n> > * \\context This function is \\threadsafe.\n> > *\n> > - * \\return True if the devices could be locked, false otherwise\n> > - * \\sa unlock()\n> > - * \\sa MediaDevice::lock()\n> > + * \\return True if the pipeline handler was acquired, false if another process\n> > + * has already acquired it\n> > + * \\sa release()\n> > */\n> > -bool PipelineHandler::lock()\n> > +bool PipelineHandler::acquire()\n> > {\n> > MutexLocker locker(lock_);\n> >\n> > - /* Do not allow nested locking in the same libcamera instance. */\n> > - if (lockOwner_)\n> > - return false;\n> > + if (useCount_) {\n> > + ++useCount_;\n> > + return true;\n> > + }\n> >\n> > for (std::shared_ptr &media : mediaDevices_) {\n> > if (!media->lock()) {\n> > - unlock();\n> > + unlockMediaDevices();\n> > return false;\n> > }\n> > }\n> >\n> > - lockOwner_ = true;\n> > -\n> > + ++useCount_;\n> > return true;\n> > }\n> >\n> > /**\n> > - * \\brief Unlock all media devices acquired by the pipeline\n> > + * \\brief Release exclusive access to the pipeline handler\n> > *\n> > - * This function shall not be called from pipeline handler implementation, as\n> > - * the Camera class handles locking directly.\n> > + * This function releases access to the pipeline handler previously acquired by\n> > + * a call to acquire(). Every release() call shall match a previous successful\n> > + * acquire() call. Calling this function on a pipeline handler that hasn't been\n> > + * acquired results in undefined behaviour.\n> > + *\n> > + * Pipeline handlers shall not call this function directly as the Camera class\n> > + * handles access internally.\n> > *\n> > * \\context This function is \\threadsafe.\n> > *\n> > - * \\sa lock()\n> > + * \\sa acquire()\n> > */\n> > -void PipelineHandler::unlock()\n> > +void PipelineHandler::release()\n> > {\n> > MutexLocker locker(lock_);\n> >\n> > - if (!lockOwner_)\n> > - return;\n> > + ASSERT(useCount_);\n> >\n> > + unlockMediaDevices();\n> > +\n> > + --useCount_;\n> > +}\n> > +\n> > +void PipelineHandler::unlockMediaDevices()\n> > +{\n> > for (std::shared_ptr &media : mediaDevices_)\n> > media->unlock();\n> > -\n> > - lockOwner_ = false;\n> > }\n> >\n> > /**\n> >\n> > base-commit: d4eee094e684806dbdb54fbe1bc02c9c590aa7f4\n> > --\n> > Regards,\n> >\n> > Laurent Pinchart\n> >","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id ACBFDBE173\n\tfor ;\n\tWed, 10 Aug 2022 15:25:09 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 0FEDD6332B;\n\tWed, 10 Aug 2022 17:25:09 +0200 (CEST)","from mail-ej1-x62a.google.com (mail-ej1-x62a.google.com\n\t[IPv6:2a00:1450:4864:20::62a])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 6319F600EA\n\tfor ;\n\tWed, 10 Aug 2022 17:25:06 +0200 (CEST)","by mail-ej1-x62a.google.com with SMTP id gk3so28311311ejb.8\n\tfor ;\n\tWed, 10 Aug 2022 08:25:06 -0700 (PDT)"],"DKIM-Signature":["v=1; 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charset=\"UTF-8\"","Subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","From":"David Plowman via libcamera-devel ","Reply-To":"David Plowman ","Cc":"libcamera devel ","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":24523,"web_url":"https://patchwork.libcamera.org/comment/24523/","msgid":"<166015050427.15821.11318304832071515549@Monstersaurus>","date":"2022-08-10T16:55:04","subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Laurent,\n\nQuoting David Plowman (2022-08-10 16:24:55)\n> Hi Kieran, Laurent\n> \n> On Wed, 10 Aug 2022 at 16:07, Kieran Bingham\n> wrote:\n> >\n> > Hi Laurent,\n> >\n> > Quoting Laurent Pinchart (2022-07-21 22:03:51)\n> > > libcamera implements a pipeline handler locking mechanism based on\n> > > advisory locks on media devices, to prevent concurrent access to cameras\n> > > from the same pipeline handler from different processes (this only works\n> > > between multiple libcamera instances, as other processes won't use\n> > > advisory locks on media devices).\n> > >\n> > > A side effect of the implementation prevents multiple cameras created by\n> > > the same pipeline handler from being used concurrently. Fix this by\n> > > turning the PipelineHandler lock() and unlock() functions into acquire()\n> > > and release(), with a use count to replace the boolean lock flag. The\n> > > Camera class is updated accordingly.\n> > >\n> > > Signed-off-by: Laurent Pinchart \n> > > ---\n> > > This may help addressing the problem reported in \"[RFC PATCH] qcam: Fix\n> > > IPU3 camera switching\".\n> >\n> > This does indeed fix things for me on IPU3 testing with qcam.\n> > It however seemed to introduce a regression in CTS (which perhaps\n> > Harvey's patches will then resolve)\n\nI've re-run this through CTS, and the regression is (unsurprisingly):\n\n android.hardware.camera2.cts.MultiViewTest#testDualCameraPreview\n\n android.hardware.camera2.CameraAccessException: CAMERA_ERROR (3): endConfigure:513: Camera 1: Error configuring streams: Function not implemented (-38)\n\tat android.hardware.camera2.CameraManager.throwAsPublicException(CameraManager.java:810)\n\tat android.hardware.camera2.impl.ICameraDeviceUserWrapper.endConfigure(ICameraDeviceUserWrapper.java:115)\n\tat android.hardware.camera2.impl.CameraDeviceImpl.configureStreamsChecked(CameraDeviceImpl.java:480)\n\tat android.hardware.camera2.impl.CameraDeviceImpl.createCaptureSessionInternal(CameraDeviceImpl.java:680)\n\tat android.hardware.camera2.impl.CameraDeviceImpl.createCaptureSession(CameraDeviceImpl.java:523)\n\tat android.hardware.camera2.cts.CameraTestUtils.configureCameraSession(CameraTestUtils.java:770)\n\tat android.hardware.camera2.cts.CameraTestUtils.configureCameraSession(CameraTestUtils.java:911)\n\tat android.hardware.camera2.cts.testcases.Camera2MultiViewTestCase$CameraHolder.startPreview(Camera2MultiViewTestCase.java:490)\n\tat android.hardware.camera2.cts.testcases.Camera2MultiViewTestCase.startPreview(Camera2MultiViewTestCase.java:252)\n\tat android.hardware.camera2.cts.MultiViewTest.startTextureViewPreview(MultiViewTest.java:881)\n\tat android.hardware.camera2.cts.MultiViewTest.testDualCameraPreview(MultiViewTest.java:228)\n\tat java.lang.reflect.Method.invoke(Native Method)\n\tat android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:220)\n\tat android.test.InstrumentationTestCase.runTest(InstrumentationTestCase.java:205)\n\tat android.test.ActivityInstrumentationTestCase2.runTest(ActivityInstrumentationTestCase2.java:192)\n\tat junit.framework.TestCase.runBare(TestCase.java:134)\n\tat junit.framework.TestResult$1.protect(TestResult.java:115)\n\tat androidx.test.internal.runner.junit3.AndroidTestResult.runProtected(AndroidTestResult.java:73)\n\tat junit.framework.TestResult.run(TestResult.java:118)\n\tat androidx.test.internal.runner.junit3.AndroidTestResult.run(AndroidTestResult.java:51)\n\tat junit.framework.TestCase.run(TestCase.java:124)\n\tat androidx.test.internal.runner.junit3.NonLeakyTestSuite$NonLeakyTest.run(NonLeakyTestSuite.java:62)\n\tat androidx.test.internal.runner.junit3.AndroidTestSuite$2.run(AndroidTestSuite.java:101)\n\tat java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:458)\n\tat java.util.concurrent.FutureTask.run(FutureTask.java:266)\n\tat java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)\n\tat java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)\n\tat java.lang.Thread.run(Thread.java:764)\nCaused by: android.os.ServiceSpecificException: endConfigure:513: Camera 1: Error configuring streams: Function not implemented (-38) (code 10)\n\tat android.os.Parcel.createException(Parcel.java:1964)\n\tat android.os.Parcel.readException(Parcel.java:1918)\n\tat android.os.Parcel.readException(Parcel.java:1868)\n\tat android.hardware.camera2.ICameraDeviceUser$Stub$Proxy.endConfigure(ICameraDeviceUser.java:451)\n\tat android.hardware.camera2.impl.ICameraDeviceUserWrapper.endConfigure(ICameraDeviceUserWrapper.java:112)\n\t... 26 more\n\nGiven we'll know the exact cause of this regression, it's a single test\nfail; it's already not supported, and we anticipate a solution\ncoming from the ChromeOS team - I don't mind merging this patch early\nwith the regression noted.\n\n--\nKieran\n\n\n\n> >\n> > However, I think we'll hear from David that this would benefit the RPi\n> > platform already...\n> \n> Yes, this does fix something for me\n> (https://github.com/raspberrypi/picamera2/issues/229), so I'd be very\n> happy to see it merged! In my case the real problem was that lock()\n> calls unlock() when it fails, and unlock() tries to grab the mutex\n> that lock() already took. But I can certainly add this for this patch:\n> \n> Tested-by: David Plowman \n> \n> Thanks!\n> \n> David\n> \n> >\n> >\n> > Reviewed-by: Kieran Bingham \n> >\n> > > ---\n> > > include/libcamera/internal/camera.h | 1 +\n> > > include/libcamera/internal/pipeline_handler.h | 8 ++-\n> > > src/libcamera/camera.cpp | 12 +++-\n> > > src/libcamera/pipeline_handler.cpp | 63 ++++++++++++-------\n> > > 4 files changed, 55 insertions(+), 29 deletions(-)\n> > >\n> > > diff --git a/include/libcamera/internal/camera.h b/include/libcamera/internal/camera.h\n> > > index 597426a6f9d2..38dd94ff8156 100644\n> > > --- a/include/libcamera/internal/camera.h\n> > > +++ b/include/libcamera/internal/camera.h\n> > > @@ -50,6 +50,7 @@ private:\n> > > CameraRunning,\n> > > };\n> > >\n> > > + bool isAcquired() const;\n> > > bool isRunning() const;\n> > > int isAccessAllowed(State state, bool allowDisconnected = false,\n> > > const char *from = __builtin_FUNCTION()) const;\n> > > diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h\n> > > index c3e4c2587ecd..20f1cbb07fea 100644\n> > > --- a/include/libcamera/internal/pipeline_handler.h\n> > > +++ b/include/libcamera/internal/pipeline_handler.h\n> > > @@ -45,8 +45,8 @@ public:\n> > > MediaDevice *acquireMediaDevice(DeviceEnumerator *enumerator,\n> > > const DeviceMatch &dm);\n> > >\n> > > - bool lock();\n> > > - void unlock();\n> > > + bool acquire();\n> > > + void release();\n> > >\n> > > virtual CameraConfiguration *generateConfiguration(Camera *camera,\n> > > const StreamRoles &roles) = 0;\n> > > @@ -77,6 +77,8 @@ protected:\n> > > CameraManager *manager_;\n> > >\n> > > private:\n> > > + void unlockMediaDevices();\n> > > +\n> > > void mediaDeviceDisconnected(MediaDevice *media);\n> > > virtual void disconnect();\n> > >\n> > > @@ -91,7 +93,7 @@ private:\n> > > const char *name_;\n> > >\n> > > Mutex lock_;\n> > > - bool lockOwner_ LIBCAMERA_TSA_GUARDED_BY(lock_); /* *Not* ownership of lock_ */\n> > > + unsigned int useCount_ LIBCAMERA_TSA_GUARDED_BY(lock_);\n> > >\n> > > friend class PipelineHandlerFactory;\n> > > };\n> > > diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp\n> > > index 2a8ef60e3862..9ce32db1ac78 100644\n> > > --- a/src/libcamera/camera.cpp\n> > > +++ b/src/libcamera/camera.cpp\n> > > @@ -508,6 +508,11 @@ static const char *const camera_state_names[] = {\n> > > \"Running\",\n> > > };\n> > >\n> > > +bool Camera::Private::isAcquired() const\n> > > +{\n> > > + return state_.load(std::memory_order_acquire) == CameraRunning;\n> > > +}\n> > > +\n> > > bool Camera::Private::isRunning() const\n> > > {\n> > > return state_.load(std::memory_order_acquire) == CameraRunning;\n> > > @@ -811,7 +816,7 @@ int Camera::exportFrameBuffers(Stream *stream,\n> > > * not blocking, if the device has already been acquired (by the same or another\n> > > * process) the -EBUSY error code is returned.\n> > > *\n> > > - * Acquiring a camera will limit usage of any other camera(s) provided by the\n> > > + * Acquiring a camera may limit usage of any other camera(s) provided by the\n> > > * same pipeline handler to the same instance of libcamera. The limit is in\n> > > * effect until all cameras from the pipeline handler are released. Other\n> > > * instances of libcamera can still list and examine the cameras but will fail\n> > > @@ -839,7 +844,7 @@ int Camera::acquire()\n> > > if (ret < 0)\n> > > return ret == -EACCES ? -EBUSY : ret;\n> > >\n> > > - if (!d->pipe_->lock()) {\n> > > + if (!d->pipe_->acquire()) {\n> > > LOG(Camera, Info)\n> > > << \"Pipeline handler in use by another process\";\n> > > return -EBUSY;\n> > > @@ -873,7 +878,8 @@ int Camera::release()\n> > > if (ret < 0)\n> > > return ret == -EACCES ? -EBUSY : ret;\n> > >\n> > > - d->pipe_->unlock();\n> > > + if (d->isAcquired())\n> > > + d->pipe_->release();\n> > >\n> > > d->setState(Private::CameraAvailable);\n> > >\n> > > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> > > index 675405330f45..7d2d00ef45e6 100644\n> > > --- a/src/libcamera/pipeline_handler.cpp\n> > > +++ b/src/libcamera/pipeline_handler.cpp\n> > > @@ -68,7 +68,7 @@ LOG_DEFINE_CATEGORY(Pipeline)\n> > > * respective factories.\n> > > */\n> > > PipelineHandler::PipelineHandler(CameraManager *manager)\n> > > - : manager_(manager), lockOwner_(false)\n> > > + : manager_(manager), useCount_(0)\n> > > {\n> > > }\n> > >\n> > > @@ -143,58 +143,75 @@ MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,\n> > > }\n> > >\n> > > /**\n> > > - * \\brief Lock all media devices acquired by the pipeline\n> > > + * \\brief Acquire exclusive access to the pipeline handler for the process\n> > > *\n> > > - * This function shall not be called from pipeline handler implementation, as\n> > > - * the Camera class handles locking directly.\n> > > + * This function locks all the media devices used by the pipeline to ensure\n> > > + * that no other process can access them concurrently.\n> > > + *\n> > > + * Access to a pipeline handler may be acquired recursively from within the\n> > > + * same process. Every successful acquire() call shall be matched with a\n> > > + * release() call. This allows concurrent access to the same pipeline handler\n> > > + * from different cameras within the same process.\n> > > + *\n> > > + * Pipeline handlers shall not call this function directly as the Camera class\n> > > + * handles access internally.\n> > > *\n> > > * \\context This function is \\threadsafe.\n> > > *\n> > > - * \\return True if the devices could be locked, false otherwise\n> > > - * \\sa unlock()\n> > > - * \\sa MediaDevice::lock()\n> > > + * \\return True if the pipeline handler was acquired, false if another process\n> > > + * has already acquired it\n> > > + * \\sa release()\n> > > */\n> > > -bool PipelineHandler::lock()\n> > > +bool PipelineHandler::acquire()\n> > > {\n> > > MutexLocker locker(lock_);\n> > >\n> > > - /* Do not allow nested locking in the same libcamera instance. */\n> > > - if (lockOwner_)\n> > > - return false;\n> > > + if (useCount_) {\n> > > + ++useCount_;\n> > > + return true;\n> > > + }\n> > >\n> > > for (std::shared_ptr &media : mediaDevices_) {\n> > > if (!media->lock()) {\n> > > - unlock();\n> > > + unlockMediaDevices();\n> > > return false;\n> > > }\n> > > }\n> > >\n> > > - lockOwner_ = true;\n> > > -\n> > > + ++useCount_;\n> > > return true;\n> > > }\n> > >\n> > > /**\n> > > - * \\brief Unlock all media devices acquired by the pipeline\n> > > + * \\brief Release exclusive access to the pipeline handler\n> > > *\n> > > - * This function shall not be called from pipeline handler implementation, as\n> > > - * the Camera class handles locking directly.\n> > > + * This function releases access to the pipeline handler previously acquired by\n> > > + * a call to acquire(). Every release() call shall match a previous successful\n> > > + * acquire() call. Calling this function on a pipeline handler that hasn't been\n> > > + * acquired results in undefined behaviour.\n> > > + *\n> > > + * Pipeline handlers shall not call this function directly as the Camera class\n> > > + * handles access internally.\n> > > *\n> > > * \\context This function is \\threadsafe.\n> > > *\n> > > - * \\sa lock()\n> > > + * \\sa acquire()\n> > > */\n> > > -void PipelineHandler::unlock()\n> > > +void PipelineHandler::release()\n> > > {\n> > > MutexLocker locker(lock_);\n> > >\n> > > - if (!lockOwner_)\n> > > - return;\n> > > + ASSERT(useCount_);\n> > >\n> > > + unlockMediaDevices();\n> > > +\n> > > + --useCount_;\n> > > +}\n> > > +\n> > > +void PipelineHandler::unlockMediaDevices()\n> > > +{\n> > > for (std::shared_ptr &media : mediaDevices_)\n> > > media->unlock();\n> > > -\n> > > - lockOwner_ = false;\n> > > }\n> > >\n> > > /**\n> > >\n> > > base-commit: d4eee094e684806dbdb54fbe1bc02c9c590aa7f4\n> > > --\n> > > Regards,\n> > >\n> > > Laurent Pinchart\n> > >","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 3B027BE173\n\tfor ;\n\tWed, 10 Aug 2022 16:55:09 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 9501E6332B;\n\tWed, 10 Aug 2022 18:55:08 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 8FDE0600EA\n\tfor ;\n\tWed, 10 Aug 2022 18:55:07 +0200 (CEST)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net [86.31.172.11])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 0791F3F1;\n\tWed, 10 Aug 2022 18:55:06 +0200 (CEST)"],"DKIM-Signature":["v=1; 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dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"cjlnICNz\"; dkim-atps=neutral","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"","References":"<20220721210351.1908-1-laurent.pinchart@ideasonboard.com>\n\t<166014406801.15821.18006622305930030211@Monstersaurus>\n\t","To":"David Plowman ","Date":"Wed, 10 Aug 2022 17:55:04 +0100","Message-ID":"<166015050427.15821.11318304832071515549@Monstersaurus>","User-Agent":"alot/0.10","Subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","From":"Kieran Bingham via libcamera-devel\n\t","Reply-To":"Kieran Bingham ","Cc":"libcamera devel ","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":24524,"web_url":"https://patchwork.libcamera.org/comment/24524/","msgid":"","date":"2022-08-10T17:11:19","subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Kieran,\n\nOn Wed, Aug 10, 2022 at 05:55:04PM +0100, Kieran Bingham wrote:\n> Quoting David Plowman (2022-08-10 16:24:55)\n> > On Wed, 10 Aug 2022 at 16:07, Kieran Bingham wrote:\n> > > Quoting Laurent Pinchart (2022-07-21 22:03:51)\n> > > > libcamera implements a pipeline handler locking mechanism based on\n> > > > advisory locks on media devices, to prevent concurrent access to cameras\n> > > > from the same pipeline handler from different processes (this only works\n> > > > between multiple libcamera instances, as other processes won't use\n> > > > advisory locks on media devices).\n> > > >\n> > > > A side effect of the implementation prevents multiple cameras created by\n> > > > the same pipeline handler from being used concurrently. Fix this by\n> > > > turning the PipelineHandler lock() and unlock() functions into acquire()\n> > > > and release(), with a use count to replace the boolean lock flag. The\n> > > > Camera class is updated accordingly.\n> > > >\n> > > > Signed-off-by: Laurent Pinchart \n> > > > ---\n> > > > This may help addressing the problem reported in \"[RFC PATCH] qcam: Fix\n> > > > IPU3 camera switching\".\n> > >\n> > > This does indeed fix things for me on IPU3 testing with qcam.\n> > > It however seemed to introduce a regression in CTS (which perhaps\n> > > Harvey's patches will then resolve)\n> \n> I've re-run this through CTS, and the regression is (unsurprisingly):\n> \n> android.hardware.camera2.cts.MultiViewTest#testDualCameraPreview\n> \n> android.hardware.camera2.CameraAccessException: CAMERA_ERROR (3): endConfigure:513: Camera 1: Error configuring streams: Function not implemented (-38)\n> \tat android.hardware.camera2.CameraManager.throwAsPublicException(CameraManager.java:810)\n> \tat android.hardware.camera2.impl.ICameraDeviceUserWrapper.endConfigure(ICameraDeviceUserWrapper.java:115)\n> \tat android.hardware.camera2.impl.CameraDeviceImpl.configureStreamsChecked(CameraDeviceImpl.java:480)\n> \tat android.hardware.camera2.impl.CameraDeviceImpl.createCaptureSessionInternal(CameraDeviceImpl.java:680)\n> \tat android.hardware.camera2.impl.CameraDeviceImpl.createCaptureSession(CameraDeviceImpl.java:523)\n> \tat android.hardware.camera2.cts.CameraTestUtils.configureCameraSession(CameraTestUtils.java:770)\n> \tat android.hardware.camera2.cts.CameraTestUtils.configureCameraSession(CameraTestUtils.java:911)\n> \tat android.hardware.camera2.cts.testcases.Camera2MultiViewTestCase$CameraHolder.startPreview(Camera2MultiViewTestCase.java:490)\n> \tat android.hardware.camera2.cts.testcases.Camera2MultiViewTestCase.startPreview(Camera2MultiViewTestCase.java:252)\n> \tat android.hardware.camera2.cts.MultiViewTest.startTextureViewPreview(MultiViewTest.java:881)\n> \tat android.hardware.camera2.cts.MultiViewTest.testDualCameraPreview(MultiViewTest.java:228)\n> \tat java.lang.reflect.Method.invoke(Native Method)\n> \tat android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:220)\n> \tat android.test.InstrumentationTestCase.runTest(InstrumentationTestCase.java:205)\n> \tat android.test.ActivityInstrumentationTestCase2.runTest(ActivityInstrumentationTestCase2.java:192)\n> \tat junit.framework.TestCase.runBare(TestCase.java:134)\n> \tat junit.framework.TestResult$1.protect(TestResult.java:115)\n> \tat androidx.test.internal.runner.junit3.AndroidTestResult.runProtected(AndroidTestResult.java:73)\n> \tat junit.framework.TestResult.run(TestResult.java:118)\n> \tat androidx.test.internal.runner.junit3.AndroidTestResult.run(AndroidTestResult.java:51)\n> \tat junit.framework.TestCase.run(TestCase.java:124)\n> \tat androidx.test.internal.runner.junit3.NonLeakyTestSuite$NonLeakyTest.run(NonLeakyTestSuite.java:62)\n> \tat androidx.test.internal.runner.junit3.AndroidTestSuite$2.run(AndroidTestSuite.java:101)\n> \tat java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:458)\n> \tat java.util.concurrent.FutureTask.run(FutureTask.java:266)\n> \tat java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)\n> \tat java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)\n> \tat java.lang.Thread.run(Thread.java:764)\n> Caused by: android.os.ServiceSpecificException: endConfigure:513: Camera 1: Error configuring streams: Function not implemented (-38) (code 10)\n> \tat android.os.Parcel.createException(Parcel.java:1964)\n> \tat android.os.Parcel.readException(Parcel.java:1918)\n> \tat android.os.Parcel.readException(Parcel.java:1868)\n> \tat android.hardware.camera2.ICameraDeviceUser$Stub$Proxy.endConfigure(ICameraDeviceUser.java:451)\n> \tat android.hardware.camera2.impl.ICameraDeviceUserWrapper.endConfigure(ICameraDeviceUserWrapper.java:112)\n> \t... 26 more\n> \n> Given we'll know the exact cause of this regression, it's a single test\n> fail; it's already not supported, and we anticipate a solution\n> coming from the ChromeOS team - I don't mind merging this patch early\n> with the regression noted.\n\nI'll add the following paragraph to the commit message:\n\nAs a consequence of this change, the IPU3 pipeline handler will fail to\noperate properly when the cameras it exposes are operated concurrently.\nThe android.hardware.camera2.cts.MultiViewTest#testDualCameraPreview\ntest fails as a result. This should be fixed in the IPU3 pipeline\nhandler to implement mutual exclusion between cameras.\n\n> > > However, I think we'll hear from David that this would benefit the RPi\n> > > platform already...\n> > \n> > Yes, this does fix something for me\n> > (https://github.com/raspberrypi/picamera2/issues/229), so I'd be very\n> > happy to see it merged! In my case the real problem was that lock()\n> > calls unlock() when it fails, and unlock() tries to grab the mutex\n> > that lock() already took. But I can certainly add this for this patch:\n> > \n> > Tested-by: David Plowman \n> > \n> > Thanks!\n> > \n> > David\n> > \n> > >\n> > >\n> > > Reviewed-by: Kieran Bingham \n> > >\n> > > > ---\n> > > > include/libcamera/internal/camera.h | 1 +\n> > > > include/libcamera/internal/pipeline_handler.h | 8 ++-\n> > > > src/libcamera/camera.cpp | 12 +++-\n> > > > src/libcamera/pipeline_handler.cpp | 63 ++++++++++++-------\n> > > > 4 files changed, 55 insertions(+), 29 deletions(-)\n> > > >\n> > > > diff --git a/include/libcamera/internal/camera.h b/include/libcamera/internal/camera.h\n> > > > index 597426a6f9d2..38dd94ff8156 100644\n> > > > --- a/include/libcamera/internal/camera.h\n> > > > +++ b/include/libcamera/internal/camera.h\n> > > > @@ -50,6 +50,7 @@ private:\n> > > > CameraRunning,\n> > > > };\n> > > >\n> > > > + bool isAcquired() const;\n> > > > bool isRunning() const;\n> > > > int isAccessAllowed(State state, bool allowDisconnected = false,\n> > > > const char *from = __builtin_FUNCTION()) const;\n> > > > diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h\n> > > > index c3e4c2587ecd..20f1cbb07fea 100644\n> > > > --- a/include/libcamera/internal/pipeline_handler.h\n> > > > +++ b/include/libcamera/internal/pipeline_handler.h\n> > > > @@ -45,8 +45,8 @@ public:\n> > > > MediaDevice *acquireMediaDevice(DeviceEnumerator *enumerator,\n> > > > const DeviceMatch &dm);\n> > > >\n> > > > - bool lock();\n> > > > - void unlock();\n> > > > + bool acquire();\n> > > > + void release();\n> > > >\n> > > > virtual CameraConfiguration *generateConfiguration(Camera *camera,\n> > > > const StreamRoles &roles) = 0;\n> > > > @@ -77,6 +77,8 @@ protected:\n> > > > CameraManager *manager_;\n> > > >\n> > > > private:\n> > > > + void unlockMediaDevices();\n> > > > +\n> > > > void mediaDeviceDisconnected(MediaDevice *media);\n> > > > virtual void disconnect();\n> > > >\n> > > > @@ -91,7 +93,7 @@ private:\n> > > > const char *name_;\n> > > >\n> > > > Mutex lock_;\n> > > > - bool lockOwner_ LIBCAMERA_TSA_GUARDED_BY(lock_); /* *Not* ownership of lock_ */\n> > > > + unsigned int useCount_ LIBCAMERA_TSA_GUARDED_BY(lock_);\n> > > >\n> > > > friend class PipelineHandlerFactory;\n> > > > };\n> > > > diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp\n> > > > index 2a8ef60e3862..9ce32db1ac78 100644\n> > > > --- a/src/libcamera/camera.cpp\n> > > > +++ b/src/libcamera/camera.cpp\n> > > > @@ -508,6 +508,11 @@ static const char *const camera_state_names[] = {\n> > > > \"Running\",\n> > > > };\n> > > >\n> > > > +bool Camera::Private::isAcquired() const\n> > > > +{\n> > > > + return state_.load(std::memory_order_acquire) == CameraRunning;\n> > > > +}\n> > > > +\n> > > > bool Camera::Private::isRunning() const\n> > > > {\n> > > > return state_.load(std::memory_order_acquire) == CameraRunning;\n> > > > @@ -811,7 +816,7 @@ int Camera::exportFrameBuffers(Stream *stream,\n> > > > * not blocking, if the device has already been acquired (by the same or another\n> > > > * process) the -EBUSY error code is returned.\n> > > > *\n> > > > - * Acquiring a camera will limit usage of any other camera(s) provided by the\n> > > > + * Acquiring a camera may limit usage of any other camera(s) provided by the\n> > > > * same pipeline handler to the same instance of libcamera. The limit is in\n> > > > * effect until all cameras from the pipeline handler are released. Other\n> > > > * instances of libcamera can still list and examine the cameras but will fail\n> > > > @@ -839,7 +844,7 @@ int Camera::acquire()\n> > > > if (ret < 0)\n> > > > return ret == -EACCES ? -EBUSY : ret;\n> > > >\n> > > > - if (!d->pipe_->lock()) {\n> > > > + if (!d->pipe_->acquire()) {\n> > > > LOG(Camera, Info)\n> > > > << \"Pipeline handler in use by another process\";\n> > > > return -EBUSY;\n> > > > @@ -873,7 +878,8 @@ int Camera::release()\n> > > > if (ret < 0)\n> > > > return ret == -EACCES ? -EBUSY : ret;\n> > > >\n> > > > - d->pipe_->unlock();\n> > > > + if (d->isAcquired())\n> > > > + d->pipe_->release();\n> > > >\n> > > > d->setState(Private::CameraAvailable);\n> > > >\n> > > > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> > > > index 675405330f45..7d2d00ef45e6 100644\n> > > > --- a/src/libcamera/pipeline_handler.cpp\n> > > > +++ b/src/libcamera/pipeline_handler.cpp\n> > > > @@ -68,7 +68,7 @@ LOG_DEFINE_CATEGORY(Pipeline)\n> > > > * respective factories.\n> > > > */\n> > > > PipelineHandler::PipelineHandler(CameraManager *manager)\n> > > > - : manager_(manager), lockOwner_(false)\n> > > > + : manager_(manager), useCount_(0)\n> > > > {\n> > > > }\n> > > >\n> > > > @@ -143,58 +143,75 @@ MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,\n> > > > }\n> > > >\n> > > > /**\n> > > > - * \\brief Lock all media devices acquired by the pipeline\n> > > > + * \\brief Acquire exclusive access to the pipeline handler for the process\n> > > > *\n> > > > - * This function shall not be called from pipeline handler implementation, as\n> > > > - * the Camera class handles locking directly.\n> > > > + * This function locks all the media devices used by the pipeline to ensure\n> > > > + * that no other process can access them concurrently.\n> > > > + *\n> > > > + * Access to a pipeline handler may be acquired recursively from within the\n> > > > + * same process. Every successful acquire() call shall be matched with a\n> > > > + * release() call. This allows concurrent access to the same pipeline handler\n> > > > + * from different cameras within the same process.\n> > > > + *\n> > > > + * Pipeline handlers shall not call this function directly as the Camera class\n> > > > + * handles access internally.\n> > > > *\n> > > > * \\context This function is \\threadsafe.\n> > > > *\n> > > > - * \\return True if the devices could be locked, false otherwise\n> > > > - * \\sa unlock()\n> > > > - * \\sa MediaDevice::lock()\n> > > > + * \\return True if the pipeline handler was acquired, false if another process\n> > > > + * has already acquired it\n> > > > + * \\sa release()\n> > > > */\n> > > > -bool PipelineHandler::lock()\n> > > > +bool PipelineHandler::acquire()\n> > > > {\n> > > > MutexLocker locker(lock_);\n> > > >\n> > > > - /* Do not allow nested locking in the same libcamera instance. */\n> > > > - if (lockOwner_)\n> > > > - return false;\n> > > > + if (useCount_) {\n> > > > + ++useCount_;\n> > > > + return true;\n> > > > + }\n> > > >\n> > > > for (std::shared_ptr &media : mediaDevices_) {\n> > > > if (!media->lock()) {\n> > > > - unlock();\n> > > > + unlockMediaDevices();\n> > > > return false;\n> > > > }\n> > > > }\n> > > >\n> > > > - lockOwner_ = true;\n> > > > -\n> > > > + ++useCount_;\n> > > > return true;\n> > > > }\n> > > >\n> > > > /**\n> > > > - * \\brief Unlock all media devices acquired by the pipeline\n> > > > + * \\brief Release exclusive access to the pipeline handler\n> > > > *\n> > > > - * This function shall not be called from pipeline handler implementation, as\n> > > > - * the Camera class handles locking directly.\n> > > > + * This function releases access to the pipeline handler previously acquired by\n> > > > + * a call to acquire(). Every release() call shall match a previous successful\n> > > > + * acquire() call. Calling this function on a pipeline handler that hasn't been\n> > > > + * acquired results in undefined behaviour.\n> > > > + *\n> > > > + * Pipeline handlers shall not call this function directly as the Camera class\n> > > > + * handles access internally.\n> > > > *\n> > > > * \\context This function is \\threadsafe.\n> > > > *\n> > > > - * \\sa lock()\n> > > > + * \\sa acquire()\n> > > > */\n> > > > -void PipelineHandler::unlock()\n> > > > +void PipelineHandler::release()\n> > > > {\n> > > > MutexLocker locker(lock_);\n> > > >\n> > > > - if (!lockOwner_)\n> > > > - return;\n> > > > + ASSERT(useCount_);\n> > > >\n> > > > + unlockMediaDevices();\n> > > > +\n> > > > + --useCount_;\n> > > > +}\n> > > > +\n> > > > +void PipelineHandler::unlockMediaDevices()\n> > > > +{\n> > > > for (std::shared_ptr &media : mediaDevices_)\n> > > > media->unlock();\n> > > > -\n> > > > - lockOwner_ = false;\n> > > > }\n> > > >\n> > > > /**\n> > > >\n> > > > base-commit: d4eee094e684806dbdb54fbe1bc02c9c590aa7f4","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id B5F06C3272\n\tfor ;\n\tWed, 10 Aug 2022 17:11:34 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 3842B63328;\n\tWed, 10 Aug 2022 19:11:34 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 00118600EA\n\tfor ;\n\tWed, 10 Aug 2022 19:11:31 +0200 (CEST)","from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi\n\t[62.78.145.57])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 66A4C3F1;\n\tWed, 10 Aug 2022 19:11:31 +0200 (CEST)"],"DKIM-Signature":["v=1; 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dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"p3JKI7nn\"; dkim-atps=neutral","Date":"Wed, 10 Aug 2022 20:11:19 +0300","To":"Kieran Bingham ","Message-ID":"","References":"<20220721210351.1908-1-laurent.pinchart@ideasonboard.com>\n\t<166014406801.15821.18006622305930030211@Monstersaurus>\n\t\n\t<166015050427.15821.11318304832071515549@Monstersaurus>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","In-Reply-To":"<166015050427.15821.11318304832071515549@Monstersaurus>","Subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","From":"Laurent Pinchart via libcamera-devel\n\t","Reply-To":"Laurent Pinchart ","Cc":"libcamera devel ","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":24525,"web_url":"https://patchwork.libcamera.org/comment/24525/","msgid":"<166016653374.15821.16225479429068552849@Monstersaurus>","date":"2022-08-10T21:22:13","subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Laurent Pinchart (2022-08-10 18:11:19)\n> Hi Kieran,\n> \n> On Wed, Aug 10, 2022 at 05:55:04PM +0100, Kieran Bingham wrote:\n> > Quoting David Plowman (2022-08-10 16:24:55)\n> > > On Wed, 10 Aug 2022 at 16:07, Kieran Bingham wrote:\n> > > > Quoting Laurent Pinchart (2022-07-21 22:03:51)\n> > > > > libcamera implements a pipeline handler locking mechanism based on\n> > > > > advisory locks on media devices, to prevent concurrent access to cameras\n> > > > > from the same pipeline handler from different processes (this only works\n> > > > > between multiple libcamera instances, as other processes won't use\n> > > > > advisory locks on media devices).\n> > > > >\n> > > > > A side effect of the implementation prevents multiple cameras created by\n> > > > > the same pipeline handler from being used concurrently. Fix this by\n> > > > > turning the PipelineHandler lock() and unlock() functions into acquire()\n> > > > > and release(), with a use count to replace the boolean lock flag. The\n> > > > > Camera class is updated accordingly.\n> > > > >\n> > > > > Signed-off-by: Laurent Pinchart \n> > > > > ---\n> > > > > This may help addressing the problem reported in \"[RFC PATCH] qcam: Fix\n> > > > > IPU3 camera switching\".\n> > > >\n> > > > This does indeed fix things for me on IPU3 testing with qcam.\n> > > > It however seemed to introduce a regression in CTS (which perhaps\n> > > > Harvey's patches will then resolve)\n> > \n> > I've re-run this through CTS, and the regression is (unsurprisingly):\n> > \n> > android.hardware.camera2.cts.MultiViewTest#testDualCameraPreview\n> > \n> > android.hardware.camera2.CameraAccessException: CAMERA_ERROR (3): endConfigure:513: Camera 1: Error configuring streams: Function not implemented (-38)\n> > at android.hardware.camera2.CameraManager.throwAsPublicException(CameraManager.java:810)\n> > at android.hardware.camera2.impl.ICameraDeviceUserWrapper.endConfigure(ICameraDeviceUserWrapper.java:115)\n> > at android.hardware.camera2.impl.CameraDeviceImpl.configureStreamsChecked(CameraDeviceImpl.java:480)\n> > at android.hardware.camera2.impl.CameraDeviceImpl.createCaptureSessionInternal(CameraDeviceImpl.java:680)\n> > at android.hardware.camera2.impl.CameraDeviceImpl.createCaptureSession(CameraDeviceImpl.java:523)\n> > at android.hardware.camera2.cts.CameraTestUtils.configureCameraSession(CameraTestUtils.java:770)\n> > at android.hardware.camera2.cts.CameraTestUtils.configureCameraSession(CameraTestUtils.java:911)\n> > at android.hardware.camera2.cts.testcases.Camera2MultiViewTestCase$CameraHolder.startPreview(Camera2MultiViewTestCase.java:490)\n> > at android.hardware.camera2.cts.testcases.Camera2MultiViewTestCase.startPreview(Camera2MultiViewTestCase.java:252)\n> > at android.hardware.camera2.cts.MultiViewTest.startTextureViewPreview(MultiViewTest.java:881)\n> > at android.hardware.camera2.cts.MultiViewTest.testDualCameraPreview(MultiViewTest.java:228)\n> > at java.lang.reflect.Method.invoke(Native Method)\n> > at android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:220)\n> > at android.test.InstrumentationTestCase.runTest(InstrumentationTestCase.java:205)\n> > at android.test.ActivityInstrumentationTestCase2.runTest(ActivityInstrumentationTestCase2.java:192)\n> > at junit.framework.TestCase.runBare(TestCase.java:134)\n> > at junit.framework.TestResult$1.protect(TestResult.java:115)\n> > at androidx.test.internal.runner.junit3.AndroidTestResult.runProtected(AndroidTestResult.java:73)\n> > at junit.framework.TestResult.run(TestResult.java:118)\n> > at androidx.test.internal.runner.junit3.AndroidTestResult.run(AndroidTestResult.java:51)\n> > at junit.framework.TestCase.run(TestCase.java:124)\n> > at androidx.test.internal.runner.junit3.NonLeakyTestSuite$NonLeakyTest.run(NonLeakyTestSuite.java:62)\n> > at androidx.test.internal.runner.junit3.AndroidTestSuite$2.run(AndroidTestSuite.java:101)\n> > at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:458)\n> > at java.util.concurrent.FutureTask.run(FutureTask.java:266)\n> > at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)\n> > at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)\n> > at java.lang.Thread.run(Thread.java:764)\n> > Caused by: android.os.ServiceSpecificException: endConfigure:513: Camera 1: Error configuring streams: Function not implemented (-38) (code 10)\n> > at android.os.Parcel.createException(Parcel.java:1964)\n> > at android.os.Parcel.readException(Parcel.java:1918)\n> > at android.os.Parcel.readException(Parcel.java:1868)\n> > at android.hardware.camera2.ICameraDeviceUser$Stub$Proxy.endConfigure(ICameraDeviceUser.java:451)\n> > at android.hardware.camera2.impl.ICameraDeviceUserWrapper.endConfigure(ICameraDeviceUserWrapper.java:112)\n> > ... 26 more\n> > \n> > Given we'll know the exact cause of this regression, it's a single test\n> > fail; it's already not supported, and we anticipate a solution\n> > coming from the ChromeOS team - I don't mind merging this patch early\n> > with the regression noted.\n> \n> I'll add the following paragraph to the commit message:\n> \n> As a consequence of this change, the IPU3 pipeline handler will fail to\n> operate properly when the cameras it exposes are operated concurrently.\n> The android.hardware.camera2.cts.MultiViewTest#testDualCameraPreview\n> test fails as a result. This should be fixed in the IPU3 pipeline\n> handler to implement mutual exclusion between cameras.\n\nInteresting to note, that before this patch - the Chrome Camera App\ncan't switch cameras (much like qcam can't) - and now it can. I hope\nthat the mutual exclusion doesn't re-introduce this limitation ;-)\n\n--\nKieran","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 90DF6C3272\n\tfor ;\n\tWed, 10 Aug 2022 21:22:18 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id DD4156332B;\n\tWed, 10 Aug 2022 23:22:17 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 4586E600EA\n\tfor ;\n\tWed, 10 Aug 2022 23:22:16 +0200 (CEST)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net [86.31.172.11])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id BF8833F1;\n\tWed, 10 Aug 2022 23:22:15 +0200 (CEST)"],"DKIM-Signature":["v=1; a=rsa-sha256; c=relaxed/simple; d=libcamera.org;\n\ts=mail; t=1660166537;\n\tbh=FaK3RqduItftLegmephOXyaqfnr6WevI4fRP6JK0X/I=;\n\th=In-Reply-To:References:To:Date:Subject:List-Id:List-Unsubscribe:\n\tList-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc:\n\tFrom;\n\tb=AgXpPLSRBPZUTAI22RTQPz7T4yEPUTBizV/l3vQbxIEuxChbSlZbrlrYJBBRxFyeE\n\to8QN4ZdoQ63Wv5ajXQiTFasnx7psx2YPzNxvpEOfr5FEKCMDRw1dUKIFhGuiI3R3ej\n\tZrl+Q0r7OIOtshckcuUYQGHwdL4x/q7kNFkAOmlJS+DgN0jHG8gOZDUraj2ggwOjp1\n\t9aIkCMPXl3FhNZw/tamY5wiwLymW45dsaLuzUeqcc/8a5e3hmnHsknnEa4bVASEPup\n\ti2i5Gz8Aio+tfzI5+OrchbEr4Vz3CucgjSdMIRNASesGAv/AVMVgEoiHn3bagKx7dJ\n\th/nf51tEIPcxA==","v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1660166535;\n\tbh=FaK3RqduItftLegmephOXyaqfnr6WevI4fRP6JK0X/I=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=WiYadmW2jV4qcCu6mTSFLi1F/GTg4nz2TVNq9xHavvashLqKwDbdgR28pVu1vfGXi\n\tvjOV7c7Y4kmL1eQuiEwg/R0cWDdTN8LS32EKD0TYpdnE3VVfMB9NCKsYj2FUtxqv4c\n\tUE6GJGzdGkmUXk/O5OhZnOz+cAT/nwuFYqLkFddE="],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"WiYadmW2\"; dkim-atps=neutral","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"","References":"<20220721210351.1908-1-laurent.pinchart@ideasonboard.com>\n\t<166014406801.15821.18006622305930030211@Monstersaurus>\n\t\n\t<166015050427.15821.11318304832071515549@Monstersaurus>\n\t","To":"Laurent Pinchart ","Date":"Wed, 10 Aug 2022 22:22:13 +0100","Message-ID":"<166016653374.15821.16225479429068552849@Monstersaurus>","User-Agent":"alot/0.10","Subject":"Re: [libcamera-devel] [PATCH] libcamera: Allow concurrent use of\n\tcameras from same pipeline handler","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","From":"Kieran Bingham via libcamera-devel\n\t","Reply-To":"Kieran Bingham ","Cc":"libcamera devel ","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]