From patchwork Mon Oct 2 10:55:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sakari Ailus X-Patchwork-Id: 13405833 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 E94E6E784AF for ; Mon, 2 Oct 2023 10:56:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236597AbjJBK4l (ORCPT ); Mon, 2 Oct 2023 06:56:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236589AbjJBK4g (ORCPT ); Mon, 2 Oct 2023 06:56:36 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08243D7 for ; Mon, 2 Oct 2023 03:56:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696244191; x=1727780191; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=LBr9axdAe1dtVkwbUVU8vWSWmoYN1ROD+JSiv/iNOp4=; b=oB9m1u5ORD3B+QGxXQfIgxGis34Cug18YrPk6zqccJnXG0WMq49xtIzU l/i2J0o0CJF2gWT5AZNGEiT6/hq6U+qdnXo6TLtDp2aP4rmlFj+3izWFI u/ThQP0o/viscTiOZrcmqFtzh8UaVJNvRt/qr7PtVCAoN3ykC9i+ghxXa BL6BfZZhdUIWJIMraPCJgAcu9lVwCm2MAA21nrtGItBUlsuTKTjToaZd7 psOVDDG3HF9/UQ8GtuZiM3aWCFJBMPPNSIeKiF2bhyQl2RrVeZ3QaafoG F1Xvx0IxsNGocuOKryA83RoOyBJjvUfKHMcWF8eI9NypB9AFLTLOu9sIe Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10850"; a="379896434" X-IronPort-AV: E=Sophos;i="6.03,194,1694761200"; d="scan'208";a="379896434" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2023 03:56:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10850"; a="816251236" X-IronPort-AV: E=Sophos;i="6.03,194,1694761200"; d="scan'208";a="816251236" Received: from turnipsi.fi.intel.com (HELO kekkonen.fi.intel.com) ([10.237.72.44]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2023 03:56:25 -0700 Received: from svinhufvud.ger.corp.intel.com (localhost [IPv6:::1]) by kekkonen.fi.intel.com (Postfix) with ESMTP id 5C61A120A59; Mon, 2 Oct 2023 13:56:22 +0300 (EEST) From: Sakari Ailus To: linux-media@vger.kernel.org Cc: laurent.pinchart@ideasonboard.com, Tianshu Qiu , Bingbu Cao , Tomi Valkeinen , Jacopo Mondi , Rui Miguel Silva , Martin Kepplinger Subject: [PATCH v7 19/19] media: Documentation: Split camera sensor documentation Date: Mon, 2 Oct 2023 13:55:57 +0300 Message-Id: <20231002105557.28972-20-sakari.ailus@linux.intel.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231002105557.28972-1-sakari.ailus@linux.intel.com> References: <20231002105557.28972-1-sakari.ailus@linux.intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Split camera sensor documentation into user and kernel portions. This should make it easier for the user space developers to find the relevant documentation. Also add a list of exemplary drivers and add imx219 driver to it, besides those that were already mentioned. Signed-off-by: Sakari Ailus Reviewed-by: Laurent Pinchart Reviewed-by: Jacopo Mondi --- .../driver-api/media/camera-sensor.rst | 131 +++++------------- .../media/drivers/camera-sensor.rst | 104 ++++++++++++++ .../userspace-api/media/drivers/index.rst | 1 + .../userspace-api/media/v4l/control.rst | 4 + 4 files changed, 147 insertions(+), 93 deletions(-) create mode 100644 Documentation/userspace-api/media/drivers/camera-sensor.rst diff --git a/Documentation/driver-api/media/camera-sensor.rst b/Documentation/driver-api/media/camera-sensor.rst index 2acc08142a1a..6456145f96ed 100644 --- a/Documentation/driver-api/media/camera-sensor.rst +++ b/Documentation/driver-api/media/camera-sensor.rst @@ -1,8 +1,14 @@ .. SPDX-License-Identifier: GPL-2.0 +.. _media_writing_camera_sensor_drivers: + Writing camera sensor drivers ============================= +This document covers the in-kernel APIs only. For the best practices on +userspace API implementation in camera sensor drivers, please see +:ref:`media_using_camera_sensor_drivers`. + CSI-2 and parallel (BT.601 and BT.656) busses --------------------------------------------- @@ -34,7 +40,8 @@ Devicetree The preferred way to achieve this is using ``assigned-clocks``, ``assigned-clock-parents`` and ``assigned-clock-rates`` properties. See the -`clock device tree bindings `_ +`clock device tree bindings +`_ for more information. The driver then gets the frequency using ``clk_get_rate()``. @@ -85,9 +92,7 @@ PM instead. If you feel you need to begin calling ``.s_power()`` from an ISP or a bridge driver, instead add runtime PM support to the sensor driver you are using and drop its ``.s_power()`` handler. -See examples of runtime PM handling in e.g. ``drivers/media/i2c/ov8856.c`` and -``drivers/media/i2c/ccs/ccs-core.c``. The two drivers work in both ACPI and DT -based systems. +Please also see :ref:`examples `. Control framework ~~~~~~~~~~~~~~~~~ @@ -104,99 +109,39 @@ The function returns a non-zero value if it succeeded getting the power count or runtime PM was disabled, in either of which cases the driver may proceed to access the device. -Frame size ----------- - -There are two distinct ways to configure the frame size produced by camera -sensors. - -Freely configurable camera sensor drivers -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Freely configurable camera sensor drivers expose the device's internal -processing pipeline as one or more sub-devices with different cropping and -scaling configurations. The output size of the device is the result of a series -of cropping and scaling operations from the device's pixel array's size. - -An example of such a driver is the CCS driver (see ``drivers/media/i2c/ccs``). - -Register list based drivers -~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Register list based drivers generally, instead of able to configure the device -they control based on user requests, are limited to a number of preset -configurations that combine a number of different parameters that on hardware -level are independent. How a driver picks such configuration is based on the -format set on a source pad at the end of the device's internal pipeline. - -Most sensor drivers are implemented this way, see e.g. -``drivers/media/i2c/imx319.c`` for an example. - -Frame interval configuration ----------------------------- - -There are two different methods for obtaining possibilities for different frame -intervals as well as configuring the frame interval. Which one to implement -depends on the type of the device. - -Raw camera sensors -~~~~~~~~~~~~~~~~~~ - -Instead of a high level parameter such as frame interval, the frame interval is -a result of the configuration of a number of camera sensor implementation -specific parameters. Luckily, these parameters tend to be the same for more or -less all modern raw camera sensors. - -The frame interval is calculated using the following equation:: - - frame interval = (analogue crop width + horizontal blanking) * - (analogue crop height + vertical blanking) / pixel rate - -The formula is bus independent and is applicable for raw timing parameters on -large variety of devices beyond camera sensors. Devices that have no analogue -crop, use the full source image size, i.e. pixel array size. - -Horizontal and vertical blanking are specified by ``V4L2_CID_HBLANK`` and -``V4L2_CID_VBLANK``, respectively. The unit of the ``V4L2_CID_HBLANK`` control -is pixels and the unit of the ``V4L2_CID_VBLANK`` is lines. The pixel rate in -the sensor's **pixel array** is specified by ``V4L2_CID_PIXEL_RATE`` in the same -sub-device. The unit of that control is pixels per second. - -Register list based drivers need to implement read-only sub-device nodes for the -purpose. Devices that are not register list based need these to configure the -device's internal processing pipeline. - -The first entity in the linear pipeline is the pixel array. The pixel array may -be followed by other entities that are there to allow configuring binning, -skipping, scaling or digital crop :ref:`v4l2-subdev-selections`. - -USB cameras etc. devices -~~~~~~~~~~~~~~~~~~~~~~~~ - -USB video class hardware, as well as many cameras offering a similar higher -level interface natively, generally use the concept of frame interval (or frame -rate) on device level in firmware or hardware. This means lower level controls -implemented by raw cameras may not be used on uAPI (or even kAPI) to control the -frame interval on these devices. - Rotation, orientation and flipping ---------------------------------- -Some systems have the camera sensor mounted upside down compared to its natural -mounting rotation. In such cases, drivers shall expose the information to -userspace with the :ref:`V4L2_CID_CAMERA_SENSOR_ROTATION -` control. - -Sensor drivers shall also report the sensor's mounting orientation with the -:ref:`V4L2_CID_CAMERA_SENSOR_ORIENTATION `. - Use ``v4l2_fwnode_device_parse()`` to obtain rotation and orientation information from system firmware and ``v4l2_ctrl_new_fwnode_properties()`` to register the appropriate controls. -Sensor drivers that have any vertical or horizontal flips embedded in the -register programming sequences shall initialize the V4L2_CID_HFLIP and -V4L2_CID_VFLIP controls with the values programmed by the register sequences. -The default values of these controls shall be 0 (disabled). Especially these -controls shall not be inverted, independently of the sensor's mounting -rotation. +.. _media-camera-sensor-examples: + +Example drivers +--------------- + +Features implemented by sensor drivers vary, and depending on the set of +supported features and other qualities, particular sensor drivers better serve +the purpose of an example. The following drivers are known to be good examples: + +.. flat-table:: Example sensor drivers + :header-rows: 0 + :widths: 1 1 1 2 + + * - Driver name + - File(s) + - Driver type + - Example topic + * - CCS + - ``drivers/media/i2c/ccs/`` + - Freely configurable + - Power management (ACPI and DT), UAPI + * - imx219 + - ``drivers/media/i2c/imx219.c`` + - Register list based + - Power management (DT), UAPI, mode selection + * - imx319 + - ``drivers/media/i2c/imx319.c`` + - Register list based + - Power management (ACPI and DT) diff --git a/Documentation/userspace-api/media/drivers/camera-sensor.rst b/Documentation/userspace-api/media/drivers/camera-sensor.rst new file mode 100644 index 000000000000..919a50e8b9d9 --- /dev/null +++ b/Documentation/userspace-api/media/drivers/camera-sensor.rst @@ -0,0 +1,104 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. _media_using_camera_sensor_drivers: + +Using camera sensor drivers +=========================== + +This section describes common practices for how the V4L2 sub-device interface is +used to control the camera sensor drivers. + +You may also find :ref:`media_writing_camera_sensor_drivers` useful. + +Frame size +---------- + +There are two distinct ways to configure the frame size produced by camera +sensors. + +Freely configurable camera sensor drivers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Freely configurable camera sensor drivers expose the device's internal +processing pipeline as one or more sub-devices with different cropping and +scaling configurations. The output size of the device is the result of a series +of cropping and scaling operations from the device's pixel array's size. + +An example of such a driver is the CCS driver. + +Register list based drivers +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Register list based drivers generally, instead of able to configure the device +they control based on user requests, are limited to a number of preset +configurations that combine a number of different parameters that on hardware +level are independent. How a driver picks such configuration is based on the +format set on a source pad at the end of the device's internal pipeline. + +Most sensor drivers are implemented this way. + +Frame interval configuration +---------------------------- + +There are two different methods for obtaining possibilities for different frame +intervals as well as configuring the frame interval. Which one to implement +depends on the type of the device. + +Raw camera sensors +~~~~~~~~~~~~~~~~~~ + +Instead of a high level parameter such as frame interval, the frame interval is +a result of the configuration of a number of camera sensor implementation +specific parameters. Luckily, these parameters tend to be the same for more or +less all modern raw camera sensors. + +The frame interval is calculated using the following equation:: + + frame interval = (analogue crop width + horizontal blanking) * + (analogue crop height + vertical blanking) / pixel rate + +The formula is bus independent and is applicable for raw timing parameters on +large variety of devices beyond camera sensors. Devices that have no analogue +crop, use the full source image size, i.e. pixel array size. + +Horizontal and vertical blanking are specified by ``V4L2_CID_HBLANK`` and +``V4L2_CID_VBLANK``, respectively. The unit of the ``V4L2_CID_HBLANK`` control +is pixels and the unit of the ``V4L2_CID_VBLANK`` is lines. The pixel rate in +the sensor's **pixel array** is specified by ``V4L2_CID_PIXEL_RATE`` in the same +sub-device. The unit of that control is pixels per second. + +Register list based drivers need to implement read-only sub-device nodes for the +purpose. Devices that are not register list based need these to configure the +device's internal processing pipeline. + +The first entity in the linear pipeline is the pixel array. The pixel array may +be followed by other entities that are there to allow configuring binning, +skipping, scaling or digital crop, see :ref:`VIDIOC_SUBDEV_G_SELECTION +`. + +USB cameras etc. devices +~~~~~~~~~~~~~~~~~~~~~~~~ + +USB video class hardware, as well as many cameras offering a similar higher +level interface natively, generally use the concept of frame interval (or frame +rate) on device level in firmware or hardware. This means lower level controls +implemented by raw cameras may not be used on uAPI (or even kAPI) to control the +frame interval on these devices. + +Rotation, orientation and flipping +---------------------------------- + +Some systems have the camera sensor mounted upside down compared to its natural +mounting rotation. In such cases, drivers shall expose the information to +userspace with the :ref:`V4L2_CID_CAMERA_SENSOR_ROTATION +` control. + +Sensor drivers shall also report the sensor's mounting orientation with the +:ref:`V4L2_CID_CAMERA_SENSOR_ORIENTATION `. + +Sensor drivers that have any vertical or horizontal flips embedded in the +register programming sequences shall initialize the :ref:`V4L2_CID_HFLIP +` and :ref:`V4L2_CID_VFLIP ` controls with the +values programmed by the register sequences. The default values of these +controls shall be 0 (disabled). Especially these controls shall not be inverted, +independently of the sensor's mounting rotation. diff --git a/Documentation/userspace-api/media/drivers/index.rst b/Documentation/userspace-api/media/drivers/index.rst index 783f92f01a4c..1726f8ec86fa 100644 --- a/Documentation/userspace-api/media/drivers/index.rst +++ b/Documentation/userspace-api/media/drivers/index.rst @@ -32,6 +32,7 @@ For more details see the file COPYING in the source distribution of Linux. :numbered: aspeed-video + camera-sensor ccs cx2341x-uapi dw100 diff --git a/Documentation/userspace-api/media/v4l/control.rst b/Documentation/userspace-api/media/v4l/control.rst index 4463fce694b0..57893814a1e5 100644 --- a/Documentation/userspace-api/media/v4l/control.rst +++ b/Documentation/userspace-api/media/v4l/control.rst @@ -143,9 +143,13 @@ Control IDs recognise the difference between digital and analogue gain use controls ``V4L2_CID_DIGITAL_GAIN`` and ``V4L2_CID_ANALOGUE_GAIN``. +.. _v4l2-cid-hflip: + ``V4L2_CID_HFLIP`` ``(boolean)`` Mirror the picture horizontally. +.. _v4l2-cid-vflip: + ``V4L2_CID_VFLIP`` ``(boolean)`` Mirror the picture vertically.