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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF520C3DA7D for ; Fri, 30 Dec 2022 14:51:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235098AbiL3OvK (ORCPT ); Fri, 30 Dec 2022 09:51:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbiL3OvI (ORCPT ); Fri, 30 Dec 2022 09:51:08 -0500 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A130EDDC; Fri, 30 Dec 2022 06:51:07 -0800 (PST) Received: from pendragon.ideasonboard.com (213-243-189-158.bb.dnainternet.fi [213.243.189.158]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 0D42A2F5; Fri, 30 Dec 2022 15:51:05 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1672411866; bh=ahqWw0F7ZViaezyio1kQAwgm6ChPVpdGYJt0bI6lOCs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=M0N2tl8dmoKP1GguFOuIcDhYvcf/GZSDHb6OdYvBezMmdCyjwYsUQpTSl67v3o4Nu YXZsqFkMpxwI5P+yd4V81660MvCboXJcrUGEa4cs6sZZw6mK/mV8yJXB/8OZAho4kd 9TFDTwtPWYLNEF0gW4pUMVixTEHIqGeyVhpFToXs= Date: Fri, 30 Dec 2022 16:51:01 +0200 From: Laurent Pinchart To: Ricardo Ribalda Cc: Mauro Carvalho Chehab , "hn.chen" , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RESEND v2 8/8] media: uvcvideo: Fix hw timestampt handling for slow FPS Message-ID: References: <20220920-resend-hwtimestamp-v2-0-0d7978a817cc@chromium.org> <20220920-resend-hwtimestamp-v2-8-0d7978a817cc@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220920-resend-hwtimestamp-v2-8-0d7978a817cc@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ricardo, Thank you for the patch. On Fri, Dec 02, 2022 at 06:02:48PM +0100, Ricardo Ribalda wrote: > In UVC 1.5, when working with FPS under 32, there is a chance that the > circular buffer contains two dev_sof overflows, An explanation of why this is the case would be good in the commit message. Also, by overflow, are you talking about the SOF counter rolling over ? > but the clock interpolator > is only capable of handle a single overflow. > > Remove all the samples from the circular buffer that are two overflows > old. I would rather support multiple roll-over in the clock interpolator. Dropping older sampls will lead to less predictable behaviour and harder to debug issues. > Tested-by: HungNien Chen > Signed-off-by: Ricardo Ribalda > --- > drivers/media/usb/uvc/uvc_video.c | 15 +++++++++++++++ > drivers/media/usb/uvc/uvcvideo.h | 1 + > 2 files changed, 16 insertions(+) > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > index c81a8362d582..6b6bd521d6c2 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -471,6 +471,20 @@ static void uvc_video_clock_add_sample(struct uvc_clock *clock, > > spin_lock_irqsave(&clock->lock, flags); > > + /* Delete last overflows */ > + if (clock->head == clock->last_sof_overflow) > + clock->last_sof_overflow = -1; > + > + /* Handle overflows */ > + if (clock->count > 0 && clock->last_sof > sample->dev_sof) { > + /* Remove data from the last^2 overflows */ > + if (clock->last_sof_overflow != -1) > + clock->count = (clock->head - clock->last_sof_overflow) > + % clock->count; > + clock->last_sof_overflow = clock->head; > + } > + > + /* Add sample */ > memcpy(&clock->samples[clock->head], sample, sizeof(*sample)); > clock->last_sof = sample->dev_sof; > clock->head = (clock->head + 1) % clock->size; > @@ -594,6 +608,7 @@ static void uvc_video_clock_reset(struct uvc_clock *clock) > clock->head = 0; > clock->count = 0; > clock->last_sof = -1; > + clock->last_sof_overflow = -1; > clock->sof_offset = -1; > } > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h > index 14daa7111953..d8c520ce5a86 100644 > --- a/drivers/media/usb/uvc/uvcvideo.h > +++ b/drivers/media/usb/uvc/uvcvideo.h > @@ -647,6 +647,7 @@ struct uvc_streaming { > unsigned int head; > unsigned int count; > unsigned int size; > + unsigned int last_sof_overflow; > > u16 last_sof; > u16 sof_offset; -- Regards, Laurent Pinchart