{"id":4055,"url":"https://patchwork.libcamera.org/api/patches/4055/?format=json","web_url":"https://patchwork.libcamera.org/patch/4055/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20200616131244.70308-12-paul.elder@ideasonboard.com>","date":"2020-06-16T13:12:40","name":"[libcamera-devel,11/15] v4l2: v4l2_camera: Don't use libcamera::Semaphore for available buffers","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"1ff2d81182cab9c9dc38b04fc45d3d07b6feceb0","submitter":{"id":17,"url":"https://patchwork.libcamera.org/api/people/17/?format=json","name":"Paul Elder","email":"paul.elder@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/4055/mbox/","series":[{"id":1006,"url":"https://patchwork.libcamera.org/api/series/1006/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=1006","date":"2020-06-16T13:12:29","name":"Support v4l2-compliance","version":1,"mbox":"https://patchwork.libcamera.org/series/1006/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/4055/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/4055/checks/","tags":{},"headers":{"Return-Path":"","Received":["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 42B56603C4\n\tfor ;\n\tTue, 16 Jun 2020 15:13:21 +0200 (CEST)","from jade.flets-east.jp (unknown\n\t[IPv6:2400:4051:61:600:2807:bdfa:f6a:8e53])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id CC919F9;\n\tTue, 16 Jun 2020 15:13:19 +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=\"np8UUjBb\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1592313201;\n\tbh=yuqLnijTDViHfOA7LOUcmXFi1YyYFV/vI2MR1Bl9FmM=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=np8UUjBb3Cs4CKmbZsVv0YTXBNNE/Qtf85oNYsoFtR3XuBG81sXw0TZf7F3NaUrH4\n\tVy9tcQjqtcqNuhSw5iZnNYxQpq4R7F1ukJX2kI7G4WeBXsj20y8HwV9ewfQkczyX4V\n\tDIVbOU5jcGApOKHhg8UN4WpORehD3xTe9nEXs3Hg=","From":"Paul Elder ","To":"libcamera-devel@lists.libcamera.org","Date":"Tue, 16 Jun 2020 22:12:40 +0900","Message-Id":"<20200616131244.70308-12-paul.elder@ideasonboard.com>","X-Mailer":"git-send-email 2.27.0","In-Reply-To":"<20200616131244.70308-1-paul.elder@ideasonboard.com>","References":"<20200616131244.70308-1-paul.elder@ideasonboard.com>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Subject":"[libcamera-devel] [PATCH 11/15] 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":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","X-List-Received-Date":"Tue, 16 Jun 2020 13:13:21 -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 \n---\n src/v4l2/v4l2_camera.cpp | 32 ++++++++++++++++++++++++++++++--\n src/v4l2/v4l2_camera.h | 8 +++++++-\n src/v4l2/v4l2_camera_proxy.cpp | 11 +++++++++--\n 3 files changed, 46 insertions(+), 5 deletions(-)","diff":"diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp\nindex fdbf461..f0ec54b 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)\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 +100,9 @@ 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+\tMutexLocker locker(bufferMutex_);\n+\tbufferAvailableCount_++;\n+\tbufferCV_.notify_all();\n }\n \n int V4L2Camera::configure(StreamConfiguration *streamConfigOut,\n@@ -151,6 +153,7 @@ 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@@ -168,6 +171,7 @@ FileDescriptor V4L2Camera::getBufferFd(unsigned int index)\n \n int V4L2Camera::streamOn()\n {\n+\tMutexLocker locker(isRunningMutex_);\n \tif (isRunning_)\n \t\treturn 0;\n \n@@ -191,6 +195,7 @@ int V4L2Camera::streamOn()\n \n int V4L2Camera::streamOff()\n {\n+\tMutexLocker locker(isRunningMutex_);\n \t/* \\todo Restore buffers to reqbufs state? */\n \tif (!isRunning_)\n \t\treturn 0;\n@@ -200,12 +205,15 @@ int V4L2Camera::streamOff()\n \t\treturn ret == -EACCES ? -EBUSY : ret;\n \n \tisRunning_ = false;\n+\tbufferCV_.notify_all();\n \n \treturn 0;\n }\n \n int V4L2Camera::qbuf(unsigned int index)\n {\n+\tMutexLocker locker(isRunningMutex_);\n+\n \tstd::unique_ptr request =\n \t\tstd::unique_ptr(camera_->createRequest(index));\n \tif (!request) {\n@@ -234,3 +242,23 @@ int V4L2Camera::qbuf(unsigned int index)\n \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+}\ndiff --git a/src/v4l2/v4l2_camera.h b/src/v4l2/v4l2_camera.h\nindex 30114ed..81dcbe2 100644\n--- a/src/v4l2/v4l2_camera.h\n+++ b/src/v4l2/v4l2_camera.h\n@@ -57,7 +57,8 @@ public:\n \n \tint qbuf(unsigned int index);\n \n-\tSemaphore bufferSema_;\n+\tvoid waitForBufferAvailable();\n+\tbool isBufferAvailable();\n \n private:\n \tvoid requestComplete(Request *request);\n@@ -65,6 +66,7 @@ private:\n \tstd::shared_ptr camera_;\n \tstd::unique_ptr config_;\n \n+\tMutex isRunningMutex_;\n \tbool isRunning_;\n \n \tstd::mutex bufferLock_;\n@@ -74,6 +76,10 @@ private:\n \tstd::deque> 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 45e4656..079961a 100644\n--- a/src/v4l2/v4l2_camera_proxy.cpp\n+++ b/src/v4l2/v4l2_camera_proxy.cpp\n@@ -648,10 +648,17 @@ int V4L2CameraProxy::vidioc_dqbuf(int fd, struct v4l2_buffer *arg)\n \t\treturn -EINVAL;\n \n \tif (!nonBlockingFds_[fd])\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 dqbuf.\n+\t */\n+\tif (!streaming_)\n+\t\treturn -EINVAL;\n+\n \tupdateBuffers();\n \n \tstruct v4l2_buffer &buf = buffers_[currentBuf_];\n","prefixes":["libcamera-devel","11/15"]}