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_HELO_NONE,SPF_PASS 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 E1E41C2BBC7 for ; Tue, 14 Apr 2020 09:41:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8F3D20644 for ; Tue, 14 Apr 2020 09:41:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="ODVdxWPW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437708AbgDNJlI (ORCPT ); Tue, 14 Apr 2020 05:41:08 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:58090 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728305AbgDNJlF (ORCPT ); Tue, 14 Apr 2020 05:41:05 -0400 Received: from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi [81.175.216.236]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id EBF3D521; Tue, 14 Apr 2020 11:41:00 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1586857261; bh=miBq+nuQ2bp5VTKqnb5O2c5bKi12qjGE9ER5O2SK+kY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ODVdxWPWWD2VoTmR0JVZEaDJk68UT+zY3kEFg7LgZQTTMHfHztPdo76t+uqIMoNDJ 2ogqF+y+BIdEyXkyHfObz2gk/ndlETLd9whBHhFTzRK0ENqe139eFgPVGMZZKcZ6LC N6tkg+z5Wu2dSKqnllWEIf9wWg2GrKrTMypDfTE0= Date: Tue, 14 Apr 2020 12:40:49 +0300 From: Laurent Pinchart To: Niklas =?utf-8?Q?S=C3=B6derlund?= Cc: Helen Koike , Hans Verkuil , Sakari Ailus , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH v7 3/6] media: v4l2: Extend VIDIOC_ENUM_FMT to support MC-centric devices Message-ID: <20200414094049.GE19819@pendragon.ideasonboard.com> References: <20200413202351.1359754-1-niklas.soderlund+renesas@ragnatech.se> <20200413202351.1359754-4-niklas.soderlund+renesas@ragnatech.se> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200413202351.1359754-4-niklas.soderlund+renesas@ragnatech.se> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Niklas, On Mon, Apr 13, 2020 at 10:23:48PM +0200, Niklas Söderlund wrote: > From: Laurent Pinchart > > The VIDIOC_ENUM_FMT ioctl enumerates all formats supported by a video > node. For MC-centric devices, its behaviour has always been ill-defined, > with drivers implementing one of the following behaviours: > > - No support for VIDIOC_ENUM_FMT at all > - Enumerating all formats supported by the video node, regardless of the > configuration of the pipeline > - Enumerating formats supported by the video node for the active > configuration of the connected subdevice > > The first behaviour is obviously useless for applications. The second > behaviour provides the most information, but doesn't offer a way to find > what formats are compatible with a given pipeline configuration. The > third behaviour fixes that, but with the drawback that applications > can't enumerate all supported formats anymore, and have to modify the > active configuration of the pipeline to enumerate formats. > > The situation is messy as none of the implemented behaviours are ideal, > and userspace can't predict what will happen as the behaviour is > driver-specific. > > To fix this, let's extend the VIDIOC_ENUM_FMT with a missing capability: > enumerating pixel formats for a given media bus code. The media bus code > is passed through the v4l2_fmtdesc structure in a new mbus_code field > (repurposed from the reserved fields). With this capability in place, > applications can enumerate pixel formats for a given media bus code > without modifying the active configuration of the device. > > The current behaviour of the ioctl is preserved when the new mbus_code > field is set to 0, ensuring compatibility with existing userspace. The > API extension is documented as mandatory for MC-centric devices (as > advertised through the V4L2_CAP_IO_MC capability), allowing applications > and compliance tools to easily determine the availability of the > VIDIOC_ENUM_FMT extension. > > Signed-off-by: Laurent Pinchart Should this carry a tag from you ? :-) > --- > .../media/uapi/v4l/vidioc-enum-fmt.rst | 17 ++++++++++++++--- > drivers/media/v4l2-core/v4l2-ioctl.c | 13 +++++++++++-- > include/uapi/linux/videodev2.h | 3 ++- > 3 files changed, 27 insertions(+), 6 deletions(-) > > diff --git a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst > index 8ca6ab701e4ab99c..82792d8e910b2313 100644 > --- a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst > +++ b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst > @@ -48,10 +48,21 @@ one until ``EINVAL`` is returned. If applicable, drivers shall return > formats in preference order, where preferred formats are returned before > (that is, with lower ``index`` value) less-preferred formats. > > -.. note:: > +If the driver doesn't advertise the ``V4L2_CAP_IO_MC`` > +:ref:`device-capabilities `, applications shall initialize the > +``mbus_code`` field to zero. Drivers shall enumerate all image formats supported > +by the device. The enumerated formats may depend on the active input or output > +of the device. > > - After switching input or output the list of enumerated image > - formats may be different. > +If the driver advertises the ``V4L2_CAP_IO_MC`` :ref:`device-capabilities > +`, applications may initialize the ``mbus_code`` to a valid > +:ref:`v4l2_mbus_pixelcode `. If the ``mbus_code` field > +is not zero, drivers shall restrict enumeration to only the image formats that > +can produce (for video output devices) or be produced from (for video capture > +devices) that media bus code. Regardless of the value of the ``mbus_code`` > +field, the enumerated image formats shall not depend on the active > +configuration of the video device or device pipeline. Enumeration shall > +otherwise operate as previously described. > > > .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > index afd1f427df557f71..3e7b99fa415222c6 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -264,12 +264,13 @@ static void v4l_print_fmtdesc(const void *arg, bool write_only) > { > const struct v4l2_fmtdesc *p = arg; > > - pr_cont("index=%u, type=%s, flags=0x%x, pixelformat=%c%c%c%c, description='%.*s'\n", > + pr_cont("index=%u, type=%s, flags=0x%x, pixelformat=%c%c%c%c, mbus_code=0x%04x, description='%.*s'\n", > p->index, prt_names(p->type, v4l2_type_names), > p->flags, (p->pixelformat & 0xff), > (p->pixelformat >> 8) & 0xff, > (p->pixelformat >> 16) & 0xff, > (p->pixelformat >> 24) & 0xff, > + p->mbus_code, > (int)sizeof(p->description), p->description); > } > > @@ -1472,12 +1473,20 @@ static int v4l_enum_fmt(const struct v4l2_ioctl_ops *ops, > struct video_device *vdev = video_devdata(file); > struct v4l2_fmtdesc *p = arg; > int ret = check_fmt(file, p->type); > + u32 mbus_code; > u32 cap_mask; > > if (ret) > return ret; > ret = -EINVAL; > > + if (p->mbus_code && !(vdev->device_caps & V4L2_CAP_IO_MC)) > + return -EINVAL; > + > + mbus_code = p->mbus_code; > + CLEAR_AFTER_FIELD(p, type); > + p->mbus_code = mbus_code; > + > switch (p->type) { > case V4L2_BUF_TYPE_VIDEO_CAPTURE: > case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE: > @@ -2757,7 +2766,7 @@ DEFINE_V4L_STUB_FUNC(dv_timings_cap) > > static const struct v4l2_ioctl_info v4l2_ioctls[] = { > IOCTL_INFO(VIDIOC_QUERYCAP, v4l_querycap, v4l_print_querycap, 0), > - IOCTL_INFO(VIDIOC_ENUM_FMT, v4l_enum_fmt, v4l_print_fmtdesc, INFO_FL_CLEAR(v4l2_fmtdesc, type)), > + IOCTL_INFO(VIDIOC_ENUM_FMT, v4l_enum_fmt, v4l_print_fmtdesc, 0), > IOCTL_INFO(VIDIOC_G_FMT, v4l_g_fmt, v4l_print_format, 0), > IOCTL_INFO(VIDIOC_S_FMT, v4l_s_fmt, v4l_print_format, INFO_FL_PRIO), > IOCTL_INFO(VIDIOC_REQBUFS, v4l_reqbufs, v4l_print_requestbuffers, INFO_FL_PRIO | INFO_FL_QUEUE), > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index b18f3f7cde31c2e4..c3a1cf1c507f5506 100644 > --- a/include/uapi/linux/videodev2.h > +++ b/include/uapi/linux/videodev2.h > @@ -784,7 +784,8 @@ struct v4l2_fmtdesc { > __u32 flags; > __u8 description[32]; /* Description string */ > __u32 pixelformat; /* Format fourcc */ > - __u32 reserved[4]; > + __u32 mbus_code; /* Media bus code */ > + __u32 reserved[3]; > }; > > #define V4L2_FMT_FLAG_COMPRESSED 0x0001 -- Regards, Laurent Pinchart