{"id":9414,"url":"https://patchwork.libcamera.org/api/patches/9414/?format=json","web_url":"https://patchwork.libcamera.org/patch/9414/","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":"<20200828115507.305323-1-kieran.bingham@ideasonboard.com>","date":"2020-08-28T11:55:07","name":"[libcamera-devel] libcamera: buffer: Improve timestamp documentation","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"a99b442991232d57f59fdb3670e3bd7f938fddc3","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/?format=json","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"delegate":{"id":11,"url":"https://patchwork.libcamera.org/api/users/11/?format=json","username":"kbingham","first_name":"Kieran","last_name":"Bingham","email":"kieran.bingham@ideasonboard.com"},"mbox":"https://patchwork.libcamera.org/patch/9414/mbox/","series":[{"id":1249,"url":"https://patchwork.libcamera.org/api/series/1249/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=1249","date":"2020-08-28T11:55:07","name":"[libcamera-devel] libcamera: buffer: Improve timestamp documentation","version":1,"mbox":"https://patchwork.libcamera.org/series/1249/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/9414/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/9414/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 A04C5BF019\n\tfor ;\n\tFri, 28 Aug 2020 11:55:13 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 1B8FA628F3;\n\tFri, 28 Aug 2020 13:55:13 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id D43F16037B\n\tfor ;\n\tFri, 28 Aug 2020 13:55:11 +0200 (CEST)","from Q.local (cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net\n\t[86.31.172.11])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 3F1F3303;\n\tFri, 28 Aug 2020 13:55:11 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"KB+xAIWu\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1598615711;\n\tbh=7wtbWgL4Aqx2zdw/LjYFNNweoMk12HcaDb94DiqnurQ=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=KB+xAIWucFNEgVe46YOe0YLkwLdk9S/maiYpLwc+7F2Puva47A7XNGP1CU4KyI8Mk\n\tlUWU4IEtEsXTCb/OoDpFw7hWePB7d/hkb+EllQ0LSMjFE7CUIPqF5zWE75/FcQorWF\n\t19LmRbSelSV2mSSnqMF3Rkn3Wd2VYaXWgxK0ZB7M=","From":"Kieran Bingham ","To":"libcamera devel ","Date":"Fri, 28 Aug 2020 12:55:07 +0100","Message-Id":"<20200828115507.305323-1-kieran.bingham@ideasonboard.com>","X-Mailer":"git-send-email 2.25.1","MIME-Version":"1.0","Subject":"[libcamera-devel] [PATCH] libcamera: buffer: Improve timestamp\n\tdocumentation","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","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"The Buffer timestamp documentation is short and does not explain that\nthe timestamp is based on a monotonic time source, as opposed to the\nreal/wall-time clocks available in the system.\n\nExpand upon the statements to detail that it can not be used directly as\na wall-clock for the captured date/time without a further reference\npoint, and that by taking a reference point - the user will be bringing\nin potential inconsistencies which must be considered.\n\nSigned-off-by: Kieran Bingham \n---\n src/libcamera/buffer.cpp | 8 +++++++-\n 1 file changed, 7 insertions(+), 1 deletion(-)","diff":"diff --git a/src/libcamera/buffer.cpp b/src/libcamera/buffer.cpp\nindex a094737d0392..c08ca4234b29 100644\n--- a/src/libcamera/buffer.cpp\n+++ b/src/libcamera/buffer.cpp\n@@ -92,7 +92,13 @@ LOG_DEFINE_CATEGORY(Buffer)\n * The timestamp is expressed as a number of nanoseconds relative to the system\n * clock since an unspecified time point.\n *\n- * \\todo Be more precise on what timestamps refer to.\n+ * This timestamp is monotonic and not affected by changes in system time,\n+ * however it is still susceptible to small adjustments made by NTP.\n+ *\n+ * This clock has no specification on its time base, so can not be directly be\n+ * converted to a 'real' wall clock time without a comparable reference point.\n+ * However, continued conversions from the reference point, may bring in\n+ * inaccuracies due to changes on the real time clock which must be considered.\n */\n \n /**\n","prefixes":["libcamera-devel"]}