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=-8.4 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,USER_AGENT_SANE_1 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 15FACC4332B for ; Mon, 23 Mar 2020 10:07:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9E452206F8 for ; Mon, 23 Mar 2020 10:07:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="mQbGTsWM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727805AbgCWKHk (ORCPT ); Mon, 23 Mar 2020 06:07:40 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:43644 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727788AbgCWKHk (ORCPT ); Mon, 23 Mar 2020 06:07:40 -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 41DB2308; Mon, 23 Mar 2020 11:07:37 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1584958057; bh=fWJlKDyP773jm9IT+4RlkxQybpLpeZI58xgB096yzwc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mQbGTsWM4OYs7pxNq3TXirM9Mjk00oiU67Ns43C3O8Fc2MmsEZbI/mNw6zCeRpx7q XlpMJSvzzKMNnPAQJAlf6aWR6JrXrRAwghg8Q1OCEKPh+jMrGCqUmjOsCpL7tz2j5g lX11ZejPS6Kr8JZaa5Qz8D/NMKimvhB0U0K9GErM= Date: Mon, 23 Mar 2020 12:07:27 +0200 From: Laurent Pinchart To: Sakari Ailus Cc: linux-media@vger.kernel.org, Helen Koike , Hans Verkuil , linux-renesas-soc@vger.kernel.org, Niklas =?utf-8?Q?S=C3=B6derlund?= Subject: Re: [PATCH v6 2/5] media: v4l2: Extend VIDIOC_ENUM_FMT to support MC-centric devices Message-ID: <20200323100727.GA4768@pendragon.ideasonboard.com> References: <20200319004701.30416-1-laurent.pinchart@ideasonboard.com> <20200319004701.30416-3-laurent.pinchart@ideasonboard.com> <20200323100328.GA20664@kekkonen.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200323100328.GA20664@kekkonen.localdomain> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org Hi Sakari, On Mon, Mar 23, 2020 at 12:03:28PM +0200, Sakari Ailus wrote: > On Thu, Mar 19, 2020 at 02:46:58AM +0200, Laurent Pinchart wrote: > > 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 > > Acked-by: Sakari Ailus > > I'd address setting the reserved fields explicitly in a separate patch, > simply by removing them. As another field in the struct is assigned, the > memory is zeroed and explicit assignment is redundant. I'm not sure to follow you, what code are you referring to ? > > --- > > .../media/uapi/v4l/vidioc-enum-fmt.rst | 19 +++++++++++++++---- > > drivers/media/v4l2-core/v4l2-ioctl.c | 13 +++++++++++-- > > include/uapi/linux/videodev2.h | 3 ++- > > 3 files changed, 28 insertions(+), 7 deletions(-) > > > > diff --git a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst > > index 8ca6ab701e4a..82792d8e910b 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:: > > - > > - After switching input or output the list of enumerated image > > - formats may be different. > > +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. > > + > > +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 3545a8adf844..b55603964abd 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); > > } > > > > @@ -1467,12 +1468,20 @@ 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: > > @@ -2752,7 +2761,7 @@ 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 c793263a3705..0ece960844a5 100644 > > --- a/include/uapi/linux/videodev2.h > > +++ b/include/uapi/linux/videodev2.h > > @@ -779,7 +779,8 @@ 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