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 8DF09C43334 for ; Wed, 22 Jun 2022 09:44:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241794AbiFVJob (ORCPT ); Wed, 22 Jun 2022 05:44:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232464AbiFVJoa (ORCPT ); Wed, 22 Jun 2022 05:44:30 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B811A186C0 for ; Wed, 22 Jun 2022 02:44:29 -0700 (PDT) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 35816DD; Wed, 22 Jun 2022 11:44:28 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1655891068; bh=lQ2vzZDEJxvKUBtDn9CHk8IfP7niBL80uBurkmqa39c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EZcFHI4m5lr8zSTeJq4pXqXxCVZvinYyPWf41GgRZqM1R6DWMy6heOEIQZBmHzhCf iGoy/qUv7KiTCaQXtJ49FKIB/zkDD2SUVN310VKQDzR/OK2X27YdV9EnsEL9OPKxrQ DIP9pMNV/j52uGxvcsITN6SSD6XPGbP+lUlnz93c= Date: Wed, 22 Jun 2022 12:44:12 +0300 From: Laurent Pinchart To: Hans Verkuil Cc: linux-media@vger.kernel.org, Eugen Hristev Subject: Re: [PATCH 0/2] vb2: add (un)prepare_streaming vb2_queue ops Message-ID: References: <20220622093145.927377-1-hverkuil-cisco@xs4all.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220622093145.927377-1-hverkuil-cisco@xs4all.nl> Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Hans, On Wed, Jun 22, 2022 at 11:31:43AM +0200, Hans Verkuil wrote: > Add support for two new (un)prepare_streaming queue ops that are called > when the user calls VIDIOC_STREAMON and STREAMOFF (or closes the fh). > > This gives drivers a callback to validate the video pipeline and claim > or release streaming resources at the time that userspace indicates > that it wants to start streaming (VIDIOC_STREAMON) rather than when > the actual DMA engine kicks in (the start_streaming callback). This > is relevant for drivers that needs a minimum of X buffers before the > DMA can start. The actual pipeline validation needs to happen sooner > to avoid unnecessary errors at VIDIOC_QBUF time. > > As a bonus this allows us to move the horrible call to > v4l_vb2q_enable_media_source() in vb2_core_streamon() to the au0828 > driver (currently the only driver that uses this feature). Can we drop the horrible .enable_source() from media_device too ? :-) > That call never belonged in vb2, but it had the same purpose as the > new prepare_streaming op: validate the pipeline. > > This is a follow-up from my previous RFCv2: > > https://patchwork.linuxtv.org/project/linux-media/patch/ba4bca14-488f-94ea-48d9-e7343103c5aa@xs4all.nl/ > > I would like to get consensus for this series. I don't like it much. vb2 is already doing too much in my opinion, growing it isn't the right way to fix it. I'm still working on a new version of the V4L2 streams series that may conflict with this, I'd propose discussing the two together. > Hans Verkuil (2): > vb2: add (un)prepare_streaming queue ops > vb2/au0828: move the v4l_vb2q_enable_media_source to the au0828 driver > > .../media/common/videobuf2/videobuf2-core.c | 26 ++++++++++++++----- > drivers/media/usb/au0828/au0828-vbi.c | 2 ++ > drivers/media/usb/au0828/au0828-video.c | 1 + > include/media/videobuf2-core.h | 14 ++++++++++ > 4 files changed, 37 insertions(+), 6 deletions(-) -- Regards, Laurent Pinchart