{"id":4092,"url":"https://patchwork.libcamera.org/api/1.1/patches/4092/?format=json","web_url":"https://patchwork.libcamera.org/patch/4092/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/1.1/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":"<20200619054123.19052-13-paul.elder@ideasonboard.com>","date":"2020-06-19T05:41:18","name":"[libcamera-devel,v2,12/17] v4l2: v4l2_camera: Don't use libcamera::Semaphore for available buffers","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"1acce885032932b7d66f4f90178a6fd22ac1e597","submitter":{"id":17,"url":"https://patchwork.libcamera.org/api/1.1/people/17/?format=json","name":"Paul Elder","email":"paul.elder@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/4092/mbox/","series":[{"id":1017,"url":"https://patchwork.libcamera.org/api/1.1/series/1017/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=1017","date":"2020-06-19T05:41:06","name":"Support v4l2-compliance","version":2,"mbox":"https://patchwork.libcamera.org/series/1017/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/4092/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/4092/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 72367609A7\n\tfor ;\n\tFri, 19 Jun 2020 07:42:01 +0200 (CEST)","from jade.flets-east.jp (unknown\n\t[IPv6:2400:4051:61:600:e972:d773:e99a:4f79])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id E34FA560;\n\tFri, 19 Jun 2020 07:41:59 +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=\"OHm2W6X1\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1592545321;\n\tbh=P8VxN//P3vIGvUWSadYiGJnZywgwSjWut3in5YWpaFs=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=OHm2W6X1Ut+YVirMnHPIN8YDGhngab0sDWDQL5mrvxqsiYtCdRVLgV/wCuspm3UQh\n\tTdAyC/o3Jc+H/UNiIx/WzzQv5hKKmUNcwRlkU35WQcVMGhZ0p+TYpsvUm4Rim+wYtl\n\tam7437HKSzSFU0EV9Nui9woz6YPhffvwK2Ct62lQ=","From":"Paul Elder ","To":"libcamera-devel@lists.libcamera.org","Date":"Fri, 19 Jun 2020 14:41:18 +0900","Message-Id":"<20200619054123.19052-13-paul.elder@ideasonboard.com>","X-Mailer":"git-send-email 2.27.0","In-Reply-To":"<20200619054123.19052-1-paul.elder@ideasonboard.com>","References":"<20200619054123.19052-1-paul.elder@ideasonboard.com>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Subject":"[libcamera-devel] [PATCH v2 12/17] 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":"Fri, 19 Jun 2020 05:42:01 -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---\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 | 28 ++++++++++++++++++++++++++--\n src/v4l2/v4l2_camera.h | 7 ++++++-\n src/v4l2/v4l2_camera_proxy.cpp | 11 +++++++++--\n 3 files changed, 41 insertions(+), 5 deletions(-)","diff":"diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp\nindex 177b1ea..99d34b9 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@@ -144,6 +146,7 @@ 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 +196,7 @@ 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 +232,26 @@ 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 c157a80..515e906 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 \tbool isRunning();\n \n@@ -76,6 +77,10 @@ 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 ea9222e..2723450 100644\n--- a/src/v4l2/v4l2_camera_proxy.cpp\n+++ b/src/v4l2/v4l2_camera_proxy.cpp\n@@ -595,10 +595,17 @@ int V4L2CameraProxy::vidioc_dqbuf(V4L2CameraFile *cf, struct v4l2_buffer *arg)\n \t\treturn -EINVAL;\n \n \tif (!(cf->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 dqbuf.\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","v2","12/17"]}