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 A9AA5C433FE for ; Mon, 3 Oct 2022 14:31:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229918AbiJCObs (ORCPT ); Mon, 3 Oct 2022 10:31:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229484AbiJCObq (ORCPT ); Mon, 3 Oct 2022 10:31:46 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD390481D6 for ; Mon, 3 Oct 2022 07:31:44 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 65B66B8111E for ; Mon, 3 Oct 2022 14:31:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BE5AC433D6; Mon, 3 Oct 2022 14:31:40 +0000 (UTC) Message-ID: <2ea25584-de49-b311-14fe-8c430733bd7b@xs4all.nl> Date: Mon, 3 Oct 2022 16:31:38 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH v15 04/19] media: Documentation: Add GS_ROUTING documentation Content-Language: en-US To: Tomi Valkeinen , linux-media@vger.kernel.org, sakari.ailus@linux.intel.com, Jacopo Mondi , Laurent Pinchart , niklas.soderlund+renesas@ragnatech.se, Mauro Carvalho Chehab , Kishon Vijay Abraham , satish.nagireddy@getcruise.com, Tomasz Figa References: <20221003121852.616745-1-tomi.valkeinen@ideasonboard.com> <20221003121852.616745-5-tomi.valkeinen@ideasonboard.com> From: Hans Verkuil In-Reply-To: <20221003121852.616745-5-tomi.valkeinen@ideasonboard.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Tomi, On 10/3/22 14:18, Tomi Valkeinen wrote: > From: Jacopo Mondi > > Add documentation for VIDIOC_SUBDEV_G/S_ROUTING ioctl and add > description of multiplexed media pads and internal routing to the > V4L2-subdev documentation section. > > Signed-off-by: Jacopo Mondi > Signed-off-by: Tomi Valkeinen > Reviewed-by: Hans Verkuil > --- > .../userspace-api/media/v4l/dev-subdev.rst | 2 + > .../userspace-api/media/v4l/user-func.rst | 1 + > .../media/v4l/vidioc-subdev-g-routing.rst | 155 ++++++++++++++++++ > 3 files changed, 158 insertions(+) > create mode 100644 Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst > > diff --git a/Documentation/userspace-api/media/v4l/dev-subdev.rst b/Documentation/userspace-api/media/v4l/dev-subdev.rst > index fd1de0a73a9f..a67c2749089a 100644 > --- a/Documentation/userspace-api/media/v4l/dev-subdev.rst > +++ b/Documentation/userspace-api/media/v4l/dev-subdev.rst > @@ -29,6 +29,8 @@ will feature a character device node on which ioctls can be called to > > - negotiate image formats on individual pads > > +- inspect and modify internal data routing between pads of the same entity > + > Sub-device character device nodes, conventionally named > ``/dev/v4l-subdev*``, use major number 81. > > diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst > index 53e604bd7d60..228c1521f190 100644 > --- a/Documentation/userspace-api/media/v4l/user-func.rst > +++ b/Documentation/userspace-api/media/v4l/user-func.rst > @@ -70,6 +70,7 @@ Function Reference > vidioc-subdev-g-crop > vidioc-subdev-g-fmt > vidioc-subdev-g-frame-interval > + vidioc-subdev-g-routing > vidioc-subdev-g-selection > vidioc-subdev-querycap > vidioc-subscribe-event > diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst > new file mode 100644 > index 000000000000..6d8fc3b11352 > --- /dev/null > +++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst > @@ -0,0 +1,155 @@ > +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later > +.. c:namespace:: V4L > + > +.. _VIDIOC_SUBDEV_G_ROUTING: > + > +****************************************************** > +ioctl VIDIOC_SUBDEV_G_ROUTING, VIDIOC_SUBDEV_S_ROUTING > +****************************************************** > + > +Name > +==== > + > +VIDIOC_SUBDEV_G_ROUTING - VIDIOC_SUBDEV_S_ROUTING - Get or set routing between streams of media pads in a media entity. > + > + > +Synopsis > +======== > + > +.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_ROUTING, struct v4l2_subdev_routing *argp ) > + :name: VIDIOC_SUBDEV_G_ROUTING > + > +.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_ROUTING, struct v4l2_subdev_routing *argp ) > + :name: VIDIOC_SUBDEV_S_ROUTING > + > + > +Arguments > +========= > + > +``fd`` > + File descriptor returned by :ref:`open() `. > + > +``argp`` > + Pointer to struct :c:type:`v4l2_subdev_routing`. > + > + > +Description > +=========== > + > +These ioctls are used to get and set the routing in a media entity. > +The routing configuration determines the flows of data inside an entity. > + > +Drivers report their current routing tables using the > +``VIDIOC_SUBDEV_G_ROUTING`` ioctl and application may enable or disable routes > +with the ``VIDIOC_SUBDEV_S_ROUTING`` ioctl, by adding or removing routes and > +setting or clearing flags of the ``flags`` field of a > +struct :c:type:`v4l2_subdev_route`. > + > +All stream configurations are reset when ``VIDIOC_SUBDEV_S_ROUTING`` is called. This > +means that the userspace mut reconfigure all streams after calling the ioctl typo: mut -> must > +with e.g. ``VIDIOC_SUBDEV_S_FMT``. > + > +A special case for routing are routes marked with > +``V4L2_SUBDEV_ROUTE_FL_SOURCE`` flag. These routes are used to describe > +source endpoints on sensors and the sink fields are unused. This is very vague. As mentioned in my review for 05/19 I think this flag should be renamed to INTERNAL_SOURCE. Then the last sentence can change to: "These routes are used to describe source endpoints where the stream is internally created (such as a sensor) and so the sink fields are unused." > + > +When inspecting routes through ``VIDIOC_SUBDEV_G_ROUTING`` and the application > +provided ``num_routes`` is not big enough to contain all the available routes > +the subdevice exposes, drivers return the ENOSPC error code and adjust the > +value of the ``num_routes`` field. Application should then reserve enough memory > +for all the route entries and call ``VIDIOC_SUBDEV_G_ROUTING`` again. > + > +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| > + > +.. c:type:: v4l2_subdev_routing > + > +.. flat-table:: struct v4l2_subdev_routing > + :header-rows: 0 > + :stub-columns: 0 > + :widths: 1 1 2 > + > + * - __u32 > + - ``which`` > + - Format to modified, from enum > + :ref:`v4l2_subdev_format_whence `. > + * - struct :c:type:`v4l2_subdev_route` > + - ``routes[]`` > + - Array of struct :c:type:`v4l2_subdev_route` entries > + * - __u32 > + - ``num_routes`` > + - Number of entries of the routes array > + * - __u32 > + - ``reserved``\ [5] > + - Reserved for future extensions. Applications and drivers must set > + the array to zero. > + > +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| > + > +.. c:type:: v4l2_subdev_route > + > +.. flat-table:: struct v4l2_subdev_route > + :header-rows: 0 > + :stub-columns: 0 > + :widths: 1 1 2 > + > + * - __u32 > + - ``sink_pad`` > + - Sink pad number. > + * - __u32 > + - ``sink_stream`` > + - Sink pad stream number. > + * - __u32 > + - ``source_pad`` > + - Source pad number. > + * - __u32 > + - ``source_stream`` > + - Source pad stream number. > + * - __u32 > + - ``flags`` > + - Route enable/disable flags > + :ref:`v4l2_subdev_routing_flags `. > + * - __u32 > + - ``reserved``\ [5] > + - Reserved for future extensions. Applications and drivers must set > + the array to zero. > + > +.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| > + > +.. _v4l2-subdev-routing-flags: > + > +.. flat-table:: enum v4l2_subdev_routing_flags > + :header-rows: 0 > + :stub-columns: 0 > + :widths: 3 1 4 > + > + * - V4L2_SUBDEV_ROUTE_FL_ACTIVE > + - 0 > + - The route is enabled. Set by applications. > + * - V4L2_SUBDEV_ROUTE_FL_IMMUTABLE > + - 1 > + - The route is immutable. Set by the driver. > + * - V4L2_SUBDEV_ROUTE_FL_SOURCE > + - 2 > + - The route is a source route, and the ``sink_pad`` and ``sink_stream`` > + fields are unused. Set by the driver. Same issue as above, it's very vague. "Used to describe a route source endpoint where the stream is internally created (such as a sensor) and so the sink fields are unused." Regards, Hans > + > +Return Value > +============ > + > +On success 0 is returned, on error -1 and the ``errno`` variable is set > +appropriately. The generic error codes are described at the > +:ref:`Generic Error Codes ` chapter. > + > +ENOSPC > + The application provided ``num_routes`` is not big enough to contain > + all the available routes the subdevice exposes. > + > +EINVAL > + The sink or source pad identifiers reference a non-existing pad, or reference > + pads of different types (ie. the sink_pad identifiers refers to a source pad) > + or the sink or source stream identifiers reference a non-existing stream on > + the sink or source pad. > + > +E2BIG > + The application provided ``num_routes`` for ``VIDIOC_SUBDEV_S_ROUTING`` is > + larger than the number of routes the driver can handle.