From patchwork Thu Jan 31 18:18:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Niklas_S=C3=B6derlund?= X-Patchwork-Id: 456 Return-Path: Received: from bin-mail-out-06.binero.net (bin-mail-out-06.binero.net [195.74.38.229]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 90FC260DBC for ; Thu, 31 Jan 2019 19:19:16 +0100 (CET) X-Halon-ID: b5e44813-2584-11e9-b5ae-0050569116f7 Authorized-sender: niklas@soderlund.pp.se Received: from wyvern.c.hoisthospitality.com (unknown [217.64.245.162]) by bin-vsp-out-03.atm.binero.net (Halon) with ESMTPA id b5e44813-2584-11e9-b5ae-0050569116f7; Thu, 31 Jan 2019 19:19:14 +0100 (CET) From: =?utf-8?q?Niklas_S=C3=B6derlund?= To: libcamera-devel@lists.libcamera.org Date: Thu, 31 Jan 2019 19:18:50 +0100 Message-Id: <20190131181853.23739-4-niklas.soderlund@ragnatech.se> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190131181853.23739-1-niklas.soderlund@ragnatech.se> References: <20190131181853.23739-1-niklas.soderlund@ragnatech.se> MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH v6 3/6] libcamera: camera: Add acquire() and release() X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 31 Jan 2019 18:19:16 -0000 From: Laurent Pinchart Exclusive access must be obtained before performing operations that change the device state. Define an internal flag to track ownership and provide a means of protecting functions that change device configuration. Signed-off-by: Laurent Pinchart Reviewed-by: Niklas Söderlund Signed-off-by: Niklas Söderlund Reviewed-by: Kieran Bingham --- include/libcamera/camera.h | 5 +++++ src/libcamera/camera.cpp | 39 +++++++++++++++++++++++++++++++++++++- 2 files changed, 43 insertions(+), 1 deletion(-) diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h index a2ded62de94814c4..7e358f8c0aa093cf 100644 --- a/include/libcamera/camera.h +++ b/include/libcamera/camera.h @@ -29,6 +29,9 @@ public: Signal disconnected; + int acquire(); + void release(); + private: Camera(PipelineHandler *pipe, const std::string &name); ~Camera(); @@ -38,6 +41,8 @@ private: std::shared_ptr pipe_; std::string name_; + + bool acquired_; }; } /* namespace libcamera */ diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp index 9cec289282e4797b..500976b237bcbd2d 100644 --- a/src/libcamera/camera.cpp +++ b/src/libcamera/camera.cpp @@ -102,12 +102,14 @@ const std::string &Camera::name() const */ Camera::Camera(PipelineHandler *pipe, const std::string &name) - : pipe_(pipe->shared_from_this()), name_(name) + : pipe_(pipe->shared_from_this()), name_(name), acquired_(false) { } Camera::~Camera() { + if (acquired_) + LOG(Camera, Error) << "Removing camera while still in use"; } /** @@ -127,4 +129,39 @@ void Camera::disconnect() disconnected.emit(this); } +/** + * \brief Acquire the camera device for exclusive access + * + * After opening the device with open(), exclusive access must be obtained + * before performing operations that change the device state. This function is + * not blocking, if the device has already been acquired (by the same or another + * process) the -EBUSY error code is returned. + * + * Once exclusive access isn't needed anymore, the device should be released + * with a call to the release() function. + * + * \todo Implement exclusive access across processes. + * + * \return 0 on success or a negative error code on error. + */ +int Camera::acquire() +{ + if (acquired_) + return -EBUSY; + + acquired_ = true; + return 0; +} + +/** + * \brief Release exclusive access to the camera device + * + * Releasing the camera device allows other users to acquire exclusive access + * with the acquire() function. + */ +void Camera::release() +{ + acquired_ = false; +} + } /* namespace libcamera */