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=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 D04CAC83012 for ; Wed, 2 Dec 2020 15:31:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F7E02222E for ; Wed, 2 Dec 2020 15:31:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730399AbgLBPbZ convert rfc822-to-8bit (ORCPT ); Wed, 2 Dec 2020 10:31:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726367AbgLBPbZ (ORCPT ); Wed, 2 Dec 2020 10:31:25 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49189C0617A6 for ; Wed, 2 Dec 2020 07:30:45 -0800 (PST) Received: from lupine.hi.pengutronix.de ([2001:67c:670:100:3ad5:47ff:feaf:1a17] helo=lupine) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kkU5U-0000Zf-Vi; Wed, 02 Dec 2020 16:30:36 +0100 Received: from pza by lupine with local (Exim 4.92) (envelope-from ) id 1kkU5U-0000Ip-Bv; Wed, 02 Dec 2020 16:30:36 +0100 Message-ID: Subject: Re: [PATCH v5 09/10] media: Avoid parsing quantization and huffman tables From: Philipp Zabel To: Hans Verkuil , "Mirela Rabulea (OSS)" , mchehab@kernel.org, shawnguo@kernel.org, robh+dt@kernel.org Cc: paul.kocialkowski@bootlin.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-imx@nxp.com, s.hauer@pengutronix.de, aisheng.dong@nxp.com, daniel.baluta@nxp.com, robert.chiras@nxp.com, laurentiu.palcu@nxp.com, mark.rutland@arm.com, devicetree@vger.kernel.org, ezequiel@collabora.com, laurent.pinchart+renesas@ideasonboard.com, niklas.soderlund+renesas@ragnatech.se, dafna.hirschfeld@collabora.com, Mirela Rabulea Date: Wed, 02 Dec 2020 16:30:36 +0100 In-Reply-To: <48b58168-662c-3e4d-2e5d-1f2a14b239fe@xs4all.nl> References: <20201112030557.8540-1-mirela.rabulea@oss.nxp.com> <20201112030557.8540-10-mirela.rabulea@oss.nxp.com> <48b58168-662c-3e4d-2e5d-1f2a14b239fe@xs4all.nl> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT User-Agent: Evolution 3.30.5-1.1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:3ad5:47ff:feaf:1a17 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2020-12-02 at 13:12 +0100, Hans Verkuil wrote: > On 12/11/2020 04:05, Mirela Rabulea (OSS) wrote: > > From: Mirela Rabulea > > > > These are optional in struct v4l2_jpeg_header, so do not parse if > > not requested, save some time. > > > > Signed-off-by: Mirela Rabulea > > --- > > drivers/media/v4l2-core/v4l2-jpeg.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c b/drivers/media/v4l2-core/v4l2-jpeg.c > > index d77e04083d57..7576cd0ce6b9 100644 > > --- a/drivers/media/v4l2-core/v4l2-jpeg.c > > +++ b/drivers/media/v4l2-core/v4l2-jpeg.c > > @@ -307,6 +307,9 @@ static int jpeg_parse_quantization_tables(struct jpeg_stream *stream, > > { > > int len = jpeg_get_word_be(stream); > > > > + if (!tables) > > + return 0; > > + > > It feels more natural to check for a non-NULL out->quantization_tables > or non-NULL out->huffman_tables pointer in v4l2_jpeg_parse_header() > rather than in these low-level functions. It's weird to have this check here. Ah, now I get it. Yes, if you want to skip the entire DQT for performance reasons, it is probably better to just call jpeg_skip_segment() instead of jpeg_parse_quantization_table(). Otherwise the next jpeg_next_marker has to scan the whole quantization table for segment markers. regards Philipp