From patchwork Mon Mar 15 10:17:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marian Cichy X-Patchwork-Id: 11578 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id 6502DBD80E for ; Mon, 15 Mar 2021 10:17:33 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id 5ACC468D43; Mon, 15 Mar 2021 11:17:32 +0100 (CET) Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 9655668D3E for ; Mon, 15 Mar 2021 11:17:30 +0100 (CET) Received: from dude02.hi.pengutronix.de ([2001:67c:670:100:1d::28]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lLkHx-0008RT-TN; Mon, 15 Mar 2021 11:17:29 +0100 Received: from mci by dude02.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1lLkHx-0008VE-Kv; Mon, 15 Mar 2021 11:17:29 +0100 From: Marian Cichy To: libcamera-devel@lists.libcamera.org Date: Mon, 15 Mar 2021 11:17:25 +0100 Message-Id: <20210315101725.31371-2-m.cichy@pengutronix.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210315101725.31371-1-m.cichy@pengutronix.de> References: <20210315101725.31371-1-m.cichy@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::28 X-SA-Exim-Mail-From: mci@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: libcamera-devel@lists.libcamera.org Subject: [libcamera-devel] [PATCH v2 1/1] pipeline: simple: Use breadth-first search to setup media pipeline X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: graphics@pengutronix.de, Marian Cichy Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" When the SimplePipeline is setting up its data and media pipeline in the SimpleCameraData constructor, it merely tries to find the first valid pad and link to the next entity, starting from the camera sensor. Following this path may not always lead to a valid capture device and therefore the setup will fail on some machines. This is for example an issue when using the SimplePipeline on an i.MX-6Q with its i.MX IPU. This commit implements a different approach to setup the media-pipeline by finding the shortest path to a valid capture device, using the breadth-first search algorithm. The shortest path has a good chance to be the path from the sensor to the CSI capture device, as other paths may involve image converters, encoders or other IPU blocks and will have therefore more nodes. Signed-off-by: Marian Cichy Tested-by: Laurent Pinchart Reviewed-by: Laurent Pinchart --- changelog: - Renamed uniform-cost search to breadth-first search in commit message - Renamed uniform-cost search to breadth-first search in code comment - Rephrased comment for more generic cases - Fixed code-style issues - Include - Replace std::pair<> with struct Entity - Rename parentList to parents - Applied various suggestions to simplify code and reduce indentation - Make debug-message for found capture device more explicit - Avoid double-lookup when backtracing the parents - Drop MEDIA_LNK_FL_ENABLED/IMMUTABLE chreck --- src/libcamera/pipeline/simple/simple.cpp | 91 +++++++++++++----------- 1 file changed, 50 insertions(+), 41 deletions(-) diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp index 1fcf3671..d24d7199 100644 --- a/src/libcamera/pipeline/simple/simple.cpp +++ b/src/libcamera/pipeline/simple/simple.cpp @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -274,63 +275,71 @@ SimpleCameraData::SimpleCameraData(SimplePipelineHandler *pipe, int ret; /* - * Walk the pipeline towards the video node and store all entities - * along the way. + * Find the shortest path from the camera sensor to a video capture + * device using the breadth-first search algorithm. This heuristic will + * be most likely to skip paths that aren't suitable for the simple + * pipeline handler on more complex devices, and is guaranteed to + * produce a valid path on all devices that have a single option. + * + * For instance, on the IPU-based i.MX6Q, the shortest path will skip + * encoders and image converters, and will end in a CSI capture device. */ - MediaEntity *source = sensor; + std::unordered_set visited; + std::queue queue; - while (source) { - /* If we have reached a video node, we're done. */ - if (source->function() == MEDIA_ENT_F_IO_V4L) - break; + /* Remember at each entity where we came from. */ + std::unordered_map parents; + queue.push(sensor); - /* - * Use the first output pad that has links and follow its first - * link. - */ - MediaPad *sourcePad = nullptr; - MediaLink *sourceLink = nullptr; - for (MediaPad *pad : source->pads()) { - if ((pad->flags() & MEDIA_PAD_FL_SOURCE) && - !pad->links().empty()) { - sourcePad = pad; - sourceLink = pad->links().front(); - break; - } - } + MediaEntity *entity = nullptr; - if (!sourcePad) - return; + while (!queue.empty()) { + entity = queue.back(); + queue.pop(); - entities_.push_back({ source, sourceLink }); + /* Found the capture device. */ + if (entity->function() == MEDIA_ENT_F_IO_V4L) { + LOG(SimplePipeline, Debug) + << "Found capture device " << entity->name(); + video_ = pipe->video(entity); + break; + } - source = sourceLink->sink()->entity(); + /* The actual breadth-first search algorithm. */ + visited.insert(entity); + for (MediaPad *pad : entity->pads()) { + if (!(pad->flags() & MEDIA_PAD_FL_SOURCE)) + continue; - /* Avoid infinite loops. */ - auto iter = std::find_if(entities_.begin(), entities_.end(), - [&](const Entity &entity) { - return entity.entity == source; - }); - if (iter != entities_.end()) { - LOG(SimplePipeline, Info) << "Loop detected in pipeline"; - return; + for (MediaLink *link : pad->links()) { + MediaEntity *next = link->sink()->entity(); + if (visited.find(next) == visited.end()) { + queue.push(next); + parents.insert({ next, { entity, link } }); + } + } } } - /* - * We have a valid pipeline, get the video device and create the camera - * sensor. - */ - video_ = pipe->video(source); if (!video_) return; + /* + * With the parents, we can follow back our way from the capture device + * to the sensor. + */ + for (auto it = parents.find(entity); it != parents.end(); + it = parents.find(entity)) { + const Entity &e = it->second; + entities_.push_front(e); + entity = e.entity; + } + + /* Finally also remember the sensor. */ sensor_ = std::make_unique(sensor); ret = sensor_->init(); - if (ret) { + if (ret) sensor_.reset(); - return; - } } int SimpleCameraData::init()