[{"id":14434,"web_url":"https://patchwork.libcamera.org/comment/14434/","msgid":"","date":"2021-01-04T13:03:22","subject":"Re: [libcamera-devel] [PATCH v4 1/6] libcamera: Document sensor\n\tdriver requirements","submitter":{"id":5,"url":"https://patchwork.libcamera.org/api/people/5/","name":"Niklas Söderlund","email":"niklas.soderlund@ragnatech.se"},"content":"Hi Jacopo,\n\nThanks for your work.\n\nOn 2020-12-31 00:05:58 +0100, Jacopo Mondi wrote:\n> Document the feature an image sensor driver has to provide to be\n> fully libcamera-compliant.\n> \n> Reviewed-by: Laurent Pinchart \n> Signed-off-by: Jacopo Mondi \n> ---\n> Documentation/index.rst | 1 +\n> Documentation/meson.build | 1 +\n> Documentation/sensor_driver_requirements.rst | 64 ++++++++++++++++++++\n\nThe word separator used in filenames for Documentation/ are mixed \nbetween - and _, the most commonly used is -. Not for this series but \nmaybe we should standardize on one of them?\n\nReviewed-by: Niklas Söderlund \n\n> 3 files changed, 66 insertions(+)\n> create mode 100644 Documentation/sensor_driver_requirements.rst\n> \n> diff --git a/Documentation/index.rst b/Documentation/index.rst\n> index c49db18d52bd..285ca7c3e5ae 100644\n> --- a/Documentation/index.rst\n> +++ b/Documentation/index.rst\n> @@ -18,3 +18,4 @@\n> Pipeline Handler Writer's Guide \n> Tracing guide \n> Environment variables \n> + Sensor driver requirements \n> diff --git a/Documentation/meson.build b/Documentation/meson.build\n> index b1f5bb52474c..9950465ded6e 100644\n> --- a/Documentation/meson.build\n> +++ b/Documentation/meson.build\n> @@ -57,6 +57,7 @@ if sphinx.found()\n> 'guides/pipeline-handler.rst',\n> 'guides/tracing.rst',\n> 'index.rst',\n> + 'sensor_driver_requirements.rst',\n> '../README.rst',\n> ]\n> \n> diff --git a/Documentation/sensor_driver_requirements.rst b/Documentation/sensor_driver_requirements.rst\n> new file mode 100644\n> index 000000000000..0e658aaa03b5\n> --- /dev/null\n> +++ b/Documentation/sensor_driver_requirements.rst\n> @@ -0,0 +1,64 @@\n> +.. SPDX-License-Identifier: CC-BY-SA-4.0\n> +\n> +.. _sensor-driver-requirements:\n> +\n> +Sensor Driver Requirements\n> +==========================\n> +\n> +libcamera handles imaging devices in the CameraSensor class and defines\n> +through its API a consistent interface towards other library components.\n> +\n> +The CameraSensor class uses the V4L2 subdev kernel API to interface with the\n> +camera sensor through one or multiple sub-devices exposed in userspace by\n> +the sensor driver.\n> +\n> +In order for libcamera to be fully operational and provide to applications and\n> +pipeline handlers all the required information to interface with the camera\n> +sensor, a set of mandatory and optional features the driver has to support\n> +has been defined.\n> +\n> +Mandatory Requirements\n> +----------------------\n> +\n> +The sensor driver is assumed to be fully compliant with the V4L2 specification.\n> +\n> +The sensor driver shall support the following V4L2 controls:\n> +\n> +* `V4L2_CID_HBLANK`_\n> +* `V4L2_CID_PIXEL_RATE`_\n> +\n> +.. _V4L2_CID_HBLANK: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/ext-ctrls-image-source.html\n> +.. _V4L2_CID_PIXEL_RATE: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/ext-ctrls-image-process.html\n> +\n> +Both controls are used to compute the sensor output timings.\n> +\n> +Optional Requirements\n> +---------------------\n> +\n> +The sensor driver should support the following V4L2 controls:\n> +\n> +* `V4L2_CID_CAMERA_ORIENTATION`_\n> +* `V4L2_CID_CAMERA_SENSOR_ROTATION`_\n> +\n> +.. _V4L2_CID_CAMERA_ORIENTATION: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/ext-ctrls-camera.html\n> +.. _V4L2_CID_CAMERA_SENSOR_ROTATION: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/ext-ctrls-image-process.html\n> +\n> +The controls are used to register the camera location and orientation.\n> +\n> +The sensor driver should implement support for the V4L2 Selection API,\n> +specifically it should implement support for the\n> +`VIDIOC_SUBDEV_G_SELECTION`_ ioctl with support for the following selection\n> +targets:\n> +\n> +.. _VIDIOC_SUBDEV_G_SELECTION: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/vidioc-subdev-g-selection.html?highlight=g_selection#c.V4L.VIDIOC_SUBDEV_G_SELECTION\n> +\n> +* `V4L2_SEL_TGT_CROP_BOUNDS`_ to report the readable pixel array area size\n> +* `V4L2_SEL_TGT_CROP_DEFAULT`_ to report the active pixel array area size\n> +* `V4L2_SEL_TGT_CROP`_ to report the analogue selection rectangle\n> +\n> +Support for the selection API is scheduled to become a mandatory feature in\n> +the near future.\n> +\n> +.. _V4L2_SEL_TGT_CROP_BOUNDS: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/v4l2-selection-targets.html\n> +.. _V4L2_SEL_TGT_CROP_DEFAULT: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/v4l2-selection-targets.html\n> +.. _V4L2_SEL_TGT_CROP: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/v4l2-selection-targets.html\n> -- \n> 2.29.2\n> \n> _______________________________________________\n> libcamera-devel mailing list\n> libcamera-devel@lists.libcamera.org\n> https://lists.libcamera.org/listinfo/libcamera-devel","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 688C4C0F1C\n\tfor ;\n\tMon, 4 Jan 2021 13:03:28 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id E093962005;\n\tMon, 4 Jan 2021 14:03:27 +0100 (CET)","from mail-lf1-x12f.google.com (mail-lf1-x12f.google.com\n\t[IPv6:2a00:1450:4864:20::12f])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id AD07060110\n\tfor ;\n\tMon, 4 Jan 2021 14:03:24 +0100 (CET)","by mail-lf1-x12f.google.com with SMTP id y19so63903670lfa.13\n\tfor ;\n\tMon, 04 Jan 2021 05:03:24 -0800 (PST)","from localhost (h-209-203.A463.priv.bahnhof.se. 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