{"id":27123,"url":"https://patchwork.libcamera.org/api/1.1/patches/27123/?format=json","web_url":"https://patchwork.libcamera.org/patch/27123/","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":"<20260629163017.863145-46-barnabas.pocze@ideasonboard.com>","date":"2026-06-29T16:30:08","name":"[RFC,v1,45/54] v4l2: Use camera buffer pool","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"0b5a7000ae9029cfdd85c798a6cd369ca4d2b46b","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/1.1/people/216/?format=json","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/27123/mbox/","series":[{"id":6025,"url":"https://patchwork.libcamera.org/api/1.1/series/6025/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=6025","date":"2026-06-29T16:29:23","name":"libcamera: Split requests and buffers","version":1,"mbox":"https://patchwork.libcamera.org/series/6025/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/27123/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/27123/checks/","tags":{},"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 F1FBAC3261\n\tfor ;\n\tMon, 29 Jun 2026 16:31:36 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 9B31B65FB5;\n\tMon, 29 Jun 2026 18:31:36 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 53A5265F58\n\tfor ;\n\tMon, 29 Jun 2026 18:30:31 +0200 (CEST)","from pb-laptop.local (185.221.140.128.nat.pool.zt.hu\n\t[185.221.140.128])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 161DBE91\n\tfor ;\n\tMon, 29 Jun 2026 18:29:48 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"SQLqhFjL\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1782750588;\n\tbh=aRpYZWGIoniLqjhqzwyxfl+wM9XzsrE02kWnvo9W4Ls=;\n\th=From:To:Subject:Date:In-Reply-To:References:From;\n\tb=SQLqhFjL7V73XO++PjUqLb+HswWKpOklzGAbrd1GkmNbT/f1eUWl3+an00KacGCH1\n\tYoOcvLS3fmsM0jgZ/exBKrK3DsE//HDQWQBVBl71BpGZbjTRFlI0mv8daQsXAPz0wO\n\twrRqun1i1N/hapc4rD22QEZMRj5sYi7/gMr82Sec=","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","To":"libcamera-devel@lists.libcamera.org","Subject":"[RFC PATCH v1 45/54] v4l2: Use camera buffer pool","Date":"Mon, 29 Jun 2026 18:30:08 +0200","Message-ID":"<20260629163017.863145-46-barnabas.pocze@ideasonboard.com>","X-Mailer":"git-send-email 2.54.0","In-Reply-To":"<20260629163017.863145-1-barnabas.pocze@ideasonboard.com>","References":"<20260629163017.863145-1-barnabas.pocze@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","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","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"Port to using the camera's buffer pool.\n\nTODO: this is probably suboptimal in multiple respects\n\nSigned-off-by: Barnabás Pőcze \n---\n src/v4l2/v4l2_camera.cpp | 84 ++++++++++++++++++++++++++++------------\n src/v4l2/v4l2_camera.h | 4 +-\n 2 files changed, 63 insertions(+), 25 deletions(-)","diff":"diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp\nindex aae9fae68c..3bcf841cd0 100644\n--- a/src/v4l2/v4l2_camera.cpp\n+++ b/src/v4l2/v4l2_camera.cpp\n@@ -70,24 +70,30 @@ void V4L2Camera::unbind()\n \n void V4L2Camera::requestComplete(Request *request)\n {\n-\tif (request->status() == Request::RequestCancelled)\n-\t\treturn;\n+\tbool hasBuffer = false;\n \n \t/* We only have one stream at the moment. */\n \t{\n \t\tMutexLocker locker(bufferMutex_);\n-\t\tFrameBuffer *buffer = request->buffers().begin()->second;\n-\t\tcompletedBuffers_.emplace_back(buffer->cookie(), buffer->metadata());\n+\t\tFrameBuffer *buffer = request->findBuffer(config_->at(0).stream());\n \n-\t\tuint64_t data = 1;\n-\t\tint ret = ::write(efd_, &data, sizeof(data));\n-\t\tif (ret != sizeof(data))\n-\t\t\tLOG(V4L2Compat, Error) << \"Failed to signal eventfd POLLIN\";\n+\t\tif (buffer) {\n+\t\t\tcompletedBuffers_.emplace_back(buffer->cookie(), buffer->metadata());\n+\n+\t\t\tuint64_t data = 1;\n+\t\t\tint ret = ::write(efd_, &data, sizeof(data));\n+\t\t\tif (ret != sizeof(data))\n+\t\t\t\tLOG(V4L2Compat, Error) << \"Failed to signal eventfd POLLIN\";\n+\n+\t\t\thasBuffer = true;\n+\t\t}\n \n \t\trequest->reuse();\n+\t\tfreeRequests_.push_back(request);\n \t}\n \n-\tbufferCV_.notify_all();\n+\tif (hasBuffer)\n+\t\tbufferCV_.notify_all();\n }\n \n int V4L2Camera::configure(StreamConfiguration *streamConfigOut,\n@@ -150,6 +156,7 @@ int V4L2Camera::allocBuffers()\n \t\treturn ret;\n \n \tconst auto &buffers = bufferAllocator_->buffers(stream);\n+\tMutexLocker locker(bufferMutex_);\n \n \tfor (size_t i = 0; i < buffers.size(); i++) {\n \t\tstd::unique_ptr request = camera_->createRequest(i);\n@@ -157,6 +164,7 @@ int V4L2Camera::allocBuffers()\n \t\t\trequestPool_.clear();\n \t\t\treturn -ENOMEM;\n \t\t}\n+\t\tfreeRequests_.push_back(request.get());\n \t\trequestPool_.push_back(std::move(request));\n \n \t\tbuffers[i]->setCookie(i);\n@@ -167,9 +175,15 @@ int V4L2Camera::allocBuffers()\n \n void V4L2Camera::freeBuffers()\n {\n-\tpendingRequests_.clear();\n+\t{\n+\t\tMutexLocker locker(bufferMutex_);\n+\t\tfreeRequests_.clear();\n+\t}\n+\n \trequestPool_.clear();\n \n+\tpendingBuffers_.clear();\n+\n \tStream *stream = config_->at(0).stream();\n \tbufferAllocator_->free(stream);\n }\n@@ -199,21 +213,34 @@ int V4L2Camera::streamOn()\n \n \tisRunning_ = true;\n \n-\tfor (Request *req : pendingRequests_) {\n+\tStream *stream = config_->at(0).stream();\n+\n+\tMutexLocker locker(bufferMutex_);\n+\n+\tfor (FrameBuffer *buffer : pendingBuffers_) {\n+\t\tASSERT(!pendingBuffers_.empty());\n+\t\tRequest *req = freeRequests_.back();\n+\t\tfreeRequests_.pop_back();\n+\n+\t\treq->enableStream(stream, true);\n+\n \t\t/* \\todo What should we do if this returns -EINVAL? */\n \t\tret = camera_->queueRequest(req);\n \t\tif (ret < 0)\n \t\t\treturn ret == -EACCES ? -EBUSY : ret;\n+\n+\t\t/* \\todo error handling how? */\n+\t\tstd::ignore = camera_->addBuffer(stream, buffer);\n \t}\n \n-\tpendingRequests_.clear();\n+\tpendingBuffers_.clear();\n \n \treturn 0;\n }\n \n int V4L2Camera::streamOff()\n {\n-\tpendingRequests_.clear();\n+\tpendingBuffers_.clear();\n \n \tif (!isRunning_) {\n \t\tfor (std::unique_ptr &req : requestPool_)\n@@ -238,33 +265,42 @@ int V4L2Camera::streamOff()\n \n int V4L2Camera::qbuf(unsigned int index)\n {\n-\tif (index >= requestPool_.size()) {\n+\tStream *stream = config_->at(0).stream();\n+\tconst auto &buffers = bufferAllocator_->buffers(stream);\n+\n+\tif (index >= buffers.size()) {\n \t\tLOG(V4L2Compat, Error) << \"Invalid index\";\n \t\treturn -EINVAL;\n \t}\n-\tRequest *request = requestPool_[index].get();\n \n-\tStream *stream = config_->at(0).stream();\n-\tFrameBuffer *buffer = bufferAllocator_->buffers(stream)[index].get();\n-\tint ret = request->addBuffer(stream, buffer);\n-\tif (ret < 0) {\n-\t\tLOG(V4L2Compat, Error) << \"Can't set buffer for request\";\n-\t\treturn -ENOMEM;\n-\t}\n+\tFrameBuffer *buffer = buffers[index].get();\n \n \tif (!isRunning_) {\n-\t\tpendingRequests_.push_back(request);\n+\t\tpendingBuffers_.push_back(buffer);\n \t\treturn 0;\n \t}\n \n+\tMutexLocker locker(bufferMutex_);\n+\n+\tif (freeRequests_.empty())\n+\t\treturn -EBUSY;\n+\n+\tRequest *request = freeRequests_.back();\n+\n \trequest->controls().merge(std::move(controls_));\n+\trequest->enableStream(stream, true);\n \n-\tret = camera_->queueRequest(request);\n+\tint ret = camera_->queueRequest(request);\n \tif (ret < 0) {\n \t\tLOG(V4L2Compat, Error) << \"Can't queue request\";\n \t\treturn ret == -EACCES ? -EBUSY : ret;\n \t}\n \n+\tfreeRequests_.pop_back();\n+\n+\t/* \\todo error handling how? */\n+\tstd::ignore = camera_->addBuffer(stream, buffer);\n+\n \treturn 0;\n }\n \ndiff --git a/src/v4l2/v4l2_camera.h b/src/v4l2/v4l2_camera.h\nindex 06e37077b2..f51313ef36 100644\n--- a/src/v4l2/v4l2_camera.h\n+++ b/src/v4l2/v4l2_camera.h\n@@ -79,8 +79,10 @@ private:\n \tstd::unique_ptr bufferAllocator_;\n \n \tstd::vector> requestPool_;\n+\tstd::vector freeRequests_\n+\t\tLIBCAMERA_TSA_GUARDED_BY(bufferMutex_);\n \n-\tstd::deque pendingRequests_;\n+\tstd::deque pendingBuffers_;\n \tstd::deque completedBuffers_\n \t\tLIBCAMERA_TSA_GUARDED_BY(bufferMutex_);\n \n","prefixes":["RFC","v1","45/54"]}