From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 328F1ECDE30 for ; Wed, 17 Oct 2018 08:02:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E9860214C3 for ; Wed, 17 Oct 2018 08:02:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="OjT5spgC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E9860214C3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727866AbeJQP5R (ORCPT ); Wed, 17 Oct 2018 11:57:17 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:54158 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727787AbeJQP5C (ORCPT ); Wed, 17 Oct 2018 11:57:02 -0400 Received: from avalon.localnet (dfj612ybrt5fhg77mgycy-3.rev.dnainternet.fi [IPv6:2001:14ba:21f5:5b00:2e86:4862:ef6a:2804]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 5013B1277; Wed, 17 Oct 2018 10:02:31 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1539763351; bh=i8tQelRIexuQA8qiqi7BaH93AXnrPtlzelfeQfbOi/o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OjT5spgC5+uo8Krs/CjO1PErFDFvNgeDileHmOmr9biC4EFfGsQttBWaEzTZ+Ubfq CQmUlwqxYBZbV/+5ktbO02wMqGa0QWj+w3CGyKH0VTElRvWtZNOeofOMBrKIQw8P13 4Z8Zv7b2cX76PllUl12AAs2zRmQ/mxIwcN4ED2xA= From: Laurent Pinchart To: Heng-Ruey Hsu Cc: Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, jcliang@chromium.org, tfiga@chromium.org Subject: Re: [PATCH] media: uvcvideo: Add boottime clock support Date: Wed, 17 Oct 2018 11:02:40 +0300 Message-ID: <13883852.6N9L7C0n48@avalon> Organization: Ideas on Board Oy In-Reply-To: <20181017075242.21790-1-henryhsu@chromium.org> References: <20181017075242.21790-1-henryhsu@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Heng-Ruey, Thank you for the patch. On Wednesday, 17 October 2018 10:52:42 EEST Heng-Ruey Hsu wrote: > Android requires camera timestamps to be reported with > CLOCK_BOOTTIME to sync timestamp with other sensor sources. What's the rationale behind this, why can't CLOCK_MONOTONIC work ? If the monotonic clock has shortcomings that make its use impossible for proper synchronization, then we should consider switching to CLOCK_BOOTTIME globally in V4L2, not in selected drivers only. > Signed-off-by: Heng-Ruey Hsu > --- > drivers/media/usb/uvc/uvc_driver.c | 4 ++++ > drivers/media/usb/uvc/uvc_video.c | 2 ++ > 2 files changed, 6 insertions(+) > > diff --git a/drivers/media/usb/uvc/uvc_driver.c > b/drivers/media/usb/uvc/uvc_driver.c index d46dc432456c..a9658f38c586 > 100644 > --- a/drivers/media/usb/uvc/uvc_driver.c > +++ b/drivers/media/usb/uvc/uvc_driver.c > @@ -2287,6 +2287,8 @@ static int uvc_clock_param_get(char *buffer, const > struct kernel_param *kp) { > if (uvc_clock_param == CLOCK_MONOTONIC) > return sprintf(buffer, "CLOCK_MONOTONIC"); > + else if (uvc_clock_param == CLOCK_BOOTTIME) > + return sprintf(buffer, "CLOCK_BOOTTIME"); > else > return sprintf(buffer, "CLOCK_REALTIME"); > } > @@ -2298,6 +2300,8 @@ static int uvc_clock_param_set(const char *val, const > struct kernel_param *kp) > > if (strcasecmp(val, "monotonic") == 0) > uvc_clock_param = CLOCK_MONOTONIC; > + else if (strcasecmp(val, "boottime") == 0) > + uvc_clock_param = CLOCK_BOOTTIME; > else if (strcasecmp(val, "realtime") == 0) > uvc_clock_param = CLOCK_REALTIME; > else > diff --git a/drivers/media/usb/uvc/uvc_video.c > b/drivers/media/usb/uvc/uvc_video.c index 86a99f461fd8..d4248d5cd9cd 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -425,6 +425,8 @@ static inline ktime_t uvc_video_get_time(void) > { > if (uvc_clock_param == CLOCK_MONOTONIC) > return ktime_get(); > + else if (uvc_clock_param == CLOCK_BOOTTIME) > + return ktime_get_boottime(); > else > return ktime_get_real(); > } -- Regards, Laurent Pinchart