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{ "id": 4190, "url": "https://patchwork.libcamera.org/api/1.1/patches/4190/?format=api", "web_url": "https://patchwork.libcamera.org/patch/4190/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/1.1/projects/1/?format=api", "name": "libcamera", "link_name": "libcamera", "list_id": "libcamera_core", "list_email": "libcamera-devel@lists.libcamera.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20200623190836.53446-17-paul.elder@ideasonboard.com>", "date": "2020-06-23T19:08:30", "name": "[libcamera-devel,v3,16/22] v4l2: v4l2_camera: Don't use libcamera::Semaphore for available buffers", "commit_ref": null, "pull_url": null, "state": "superseded", "archived": false, "hash": "e465b2125fc83a569b4fb0e98c8ef41e1e878269", "submitter": { "id": 17, "url": "https://patchwork.libcamera.org/api/1.1/people/17/?format=api", "name": "Paul Elder", "email": "paul.elder@ideasonboard.com" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/4190/mbox/", "series": [ { "id": 1034, "url": "https://patchwork.libcamera.org/api/1.1/series/1034/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=1034", "date": "2020-06-23T19:08:14", "name": "Support v4l2-compliance", "version": 3, "mbox": "https://patchwork.libcamera.org/series/1034/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/4190/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/4190/checks/", "tags": {}, "headers": { "Return-Path": "<paul.elder@ideasonboard.com>", "Received": [ "from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id BE849609A7\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tTue, 23 Jun 2020 21:09:40 +0200 (CEST)", "from jade.rasen.tech (unknown\n\t[IPv6:2400:4051:61:600:8147:f2a2:a8c6:9087])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 5352D2A9;\n\tTue, 23 Jun 2020 21:09:38 +0200 (CEST)" ], "Authentication-Results": "lancelot.ideasonboard.com; dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"T/unOmDg\"; dkim-atps=neutral", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1592939380;\n\tbh=PJuPRSLIbolB5zdksKwZDo2JO1oAETllrtU3Dicb9fM=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=T/unOmDgrOm6sA3gTi+rJy4yly5GMauOpSpU9NTsIpFwaKvPngYxMbeA0q9jgd9nb\n\tOcNLB5aXdqfMtqm5ZxqHQ8dD8uAaLoRUeki+TqfxdRQ4d/d8knXRk2Z/YWOKvbCSLt\n\tzH4vuzJ4LRM2uRsOlinpnljOkroKBE+C4xajIdkc=", "From": "Paul Elder <paul.elder@ideasonboard.com>", "To": "libcamera-devel@lists.libcamera.org", "Date": "Wed, 24 Jun 2020 04:08:30 +0900", "Message-Id": "<20200623190836.53446-17-paul.elder@ideasonboard.com>", "X-Mailer": "git-send-email 2.27.0", "In-Reply-To": "<20200623190836.53446-1-paul.elder@ideasonboard.com>", "References": "<20200623190836.53446-1-paul.elder@ideasonboard.com>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Subject": "[libcamera-devel] [PATCH v3 16/22] v4l2: v4l2_camera: Don't use\n\tlibcamera::Semaphore for available buffers", "X-BeenThere": "libcamera-devel@lists.libcamera.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "X-List-Received-Date": "Tue, 23 Jun 2020 19:09:41 -0000" }, "content": "In V4L2, a blocked dqbuf should not not also block a streamoff. This\nmeans that on streamoff, the blocked dqbuf must return (with error). We\ncannot do this with the libcamera semaphore, so pull out the necessary\ncomponents of a semaphore, and put them into V4L2Camera, so that dqbuf\nfrom V4L2CameraProxy can wait on a disjunct condition of the\navailability of the semaphore or the stopping of the stream.\n\nSigned-off-by: Paul Elder <paul.elder@ideasonboard.com>\n\n---\nChanges in v3:\n- don't notify all with the lock held\n\nChanges in v2:\n- remove mutex for isRunning_\n- use V4L2Camera::isRunning() instead of V4L2CameraProxy::streaming_ in\n the dqbuf ioctl handler\n---\n src/v4l2/v4l2_camera.cpp | 30 ++++++++++++++++++++++++++++--\n src/v4l2/v4l2_camera.h | 9 +++++++--\n src/v4l2/v4l2_camera_proxy.cpp | 11 +++++++++--\n 3 files changed, 44 insertions(+), 6 deletions(-)", "diff": "diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp\nindex 177b1ea..bdf0036 100644\n--- a/src/v4l2/v4l2_camera.cpp\n+++ b/src/v4l2/v4l2_camera.cpp\n@@ -18,7 +18,7 @@ LOG_DECLARE_CATEGORY(V4L2Compat);\n \n V4L2Camera::V4L2Camera(std::shared_ptr<Camera> camera)\n \t: camera_(camera), isRunning_(false), bufferAllocator_(nullptr),\n-\t efd_(-1)\n+\t efd_(-1), bufferAvailableCount_(0)\n {\n \tcamera_->requestCompleted.connect(this, &V4L2Camera::requestComplete);\n }\n@@ -100,7 +100,11 @@ void V4L2Camera::requestComplete(Request *request)\n \tif (ret != sizeof(data))\n \t\tLOG(V4L2Compat, Error) << \"Failed to signal eventfd POLLIN\";\n \n-\tbufferSema_.release();\n+\t{\n+\t\tMutexLocker locker(bufferMutex_);\n+\t\tbufferAvailableCount_++;\n+\t}\n+\tbufferCV_.notify_all();\n }\n \n int V4L2Camera::configure(StreamConfiguration *streamConfigOut,\n@@ -144,6 +148,7 @@ int V4L2Camera::allocBuffers(unsigned int count)\n void V4L2Camera::freeBuffers()\n {\n \tStream *stream = *camera_->streams().begin();\n+\n \tbufferAllocator_->free(stream);\n }\n \n@@ -193,6 +198,7 @@ int V4L2Camera::streamOff()\n \t\treturn ret == -EACCES ? -EBUSY : ret;\n \n \tisRunning_ = false;\n+\tbufferCV_.notify_all();\n \n \treturn 0;\n }\n@@ -228,6 +234,26 @@ int V4L2Camera::qbuf(unsigned int index)\n \treturn 0;\n }\n \n+void V4L2Camera::waitForBufferAvailable()\n+{\n+\tMutexLocker locker(bufferMutex_);\n+\tbufferCV_.wait(locker, [&] {\n+\t\t\treturn bufferAvailableCount_ >= 1 || !isRunning_;\n+\t\t\t});\n+\tif (isRunning_)\n+\t\tbufferAvailableCount_--;\n+}\n+\n+bool V4L2Camera::isBufferAvailable()\n+{\n+\tMutexLocker locker(bufferMutex_);\n+\tif (bufferAvailableCount_ < 1)\n+\t\treturn false;\n+\n+\tbufferAvailableCount_--;\n+\treturn true;\n+}\n+\n bool V4L2Camera::isRunning()\n {\n \treturn isRunning_;\ndiff --git a/src/v4l2/v4l2_camera.h b/src/v4l2/v4l2_camera.h\nindex ee53c2b..515e906 100644\n--- a/src/v4l2/v4l2_camera.h\n+++ b/src/v4l2/v4l2_camera.h\n@@ -57,9 +57,10 @@ public:\n \n \tint qbuf(unsigned int index);\n \n-\tbool isRunning();\n+\tvoid waitForBufferAvailable();\n+\tbool isBufferAvailable();\n \n-\tSemaphore bufferSema_;\n+\tbool isRunning();\n \n private:\n \tvoid requestComplete(Request *request);\n@@ -76,6 +77,10 @@ private:\n \tstd::deque<std::unique_ptr<Buffer>> completedBuffers_;\n \n \tint efd_;\n+\n+\tMutex bufferMutex_;\n+\tstd::condition_variable bufferCV_;\n+\tunsigned int bufferAvailableCount_;\n };\n \n #endif /* __V4L2_CAMERA_H__ */\ndiff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp\nindex fa58585..8420e23 100644\n--- a/src/v4l2/v4l2_camera_proxy.cpp\n+++ b/src/v4l2/v4l2_camera_proxy.cpp\n@@ -594,10 +594,17 @@ int V4L2CameraProxy::vidioc_dqbuf(V4L2CameraFile *file, struct v4l2_buffer *arg)\n \t\treturn -EINVAL;\n \n \tif (!(file->nonBlocking()))\n-\t\tvcam_->bufferSema_.acquire();\n-\telse if (!vcam_->bufferSema_.tryAcquire())\n+\t\tvcam_->waitForBufferAvailable();\n+\telse if (!vcam_->isBufferAvailable())\n \t\treturn -EAGAIN;\n \n+\t/*\n+\t * We need to check here again in case stream was turned off while we\n+\t * were blocked on waitForBufferAvailable.\n+\t */\n+\tif (!vcam_->isRunning())\n+\t\treturn -EINVAL;\n+\n \tupdateBuffers();\n \n \tstruct v4l2_buffer &buf = buffers_[currentBuf_];\n", "prefixes": [ "libcamera-devel", "v3", "16/22" ] }