1 .. SPDX-License-Identifier: GPL-2.0 2 3 .. include:: <isonum.txt> 4 5 The Samsung S5P/Exynos4 FIMC driver 6 =================================== 7 8 Copyright |copy| 2012 - 2013 Samsung Electronics Co., Ltd. 9 10 The FIMC (Fully Interactive Mobile Camera) device available in Samsung 11 SoC Application Processors is an integrated camera host interface, color 12 space converter, image resizer and rotator. It's also capable of capturing 13 data from LCD controller (FIMD) through the SoC internal writeback data 14 path. There are multiple FIMC instances in the SoCs (up to 4), having 15 slightly different capabilities, like pixel alignment constraints, rotator 16 availability, LCD writeback support, etc. The driver is located at 17 drivers/media/platform/samsung/exynos4-is directory. 18 19 Supported SoCs 20 -------------- 21 22 S5PC100 (mem-to-mem only), S5PV210, Exynos4210 23 24 Supported features 25 ------------------ 26 27 - camera parallel interface capture (ITU-R.BT601/565); 28 - camera serial interface capture (MIPI-CSI2); 29 - memory-to-memory processing (color space conversion, scaling, mirror 30 and rotation); 31 - dynamic pipeline re-configuration at runtime (re-attachment of any FIMC 32 instance to any parallel video input or any MIPI-CSI front-end); 33 - runtime PM and system wide suspend/resume 34 35 Not currently supported 36 ----------------------- 37 38 - LCD writeback input 39 - per frame clock gating (mem-to-mem) 40 41 User space interfaces 42 --------------------- 43 44 Media device interface 45 ~~~~~~~~~~~~~~~~~~~~~~ 46 47 The driver supports Media Controller API as defined at :ref:`media_controller`. 48 The media device driver name is "Samsung S5P FIMC". 49 50 The purpose of this interface is to allow changing assignment of FIMC instances 51 to the SoC peripheral camera input at runtime and optionally to control internal 52 connections of the MIPI-CSIS device(s) to the FIMC entities. 53 54 The media device interface allows to configure the SoC for capturing image 55 data from the sensor through more than one FIMC instance (e.g. for simultaneous 56 viewfinder and still capture setup). 57 58 Reconfiguration is done by enabling/disabling media links created by the driver 59 during initialization. The internal device topology can be easily discovered 60 through media entity and links enumeration. 61 62 Memory-to-memory video node 63 ~~~~~~~~~~~~~~~~~~~~~~~~~~~ 64 65 V4L2 memory-to-memory interface at /dev/video? device node. This is standalone 66 video device, it has no media pads. However please note the mem-to-mem and 67 capture video node operation on same FIMC instance is not allowed. The driver 68 detects such cases but the applications should prevent them to avoid an 69 undefined behaviour. 70 71 Capture video node 72 ~~~~~~~~~~~~~~~~~~ 73 74 The driver supports V4L2 Video Capture Interface as defined at 75 :ref:`devices`. 76 77 At the capture and mem-to-mem video nodes only the multi-planar API is 78 supported. For more details see: :ref:`planar-apis`. 79 80 Camera capture subdevs 81 ~~~~~~~~~~~~~~~~~~~~~~ 82 83 Each FIMC instance exports a sub-device node (/dev/v4l-subdev?), a sub-device 84 node is also created per each available and enabled at the platform level 85 MIPI-CSI receiver device (currently up to two). 86 87 sysfs 88 ~~~~~ 89 90 In order to enable more precise camera pipeline control through the sub-device 91 API the driver creates a sysfs entry associated with "s5p-fimc-md" platform 92 device. The entry path is: /sys/platform/devices/s5p-fimc-md/subdev_conf_mode. 93 94 In typical use case there could be a following capture pipeline configuration: 95 sensor subdev -> mipi-csi subdev -> fimc subdev -> video node 96 97 When we configure these devices through sub-device API at user space, the 98 configuration flow must be from left to right, and the video node is 99 configured as last one. 100 101 When we don't use sub-device user space API the whole configuration of all 102 devices belonging to the pipeline is done at the video node driver. 103 The sysfs entry allows to instruct the capture node driver not to configure 104 the sub-devices (format, crop), to avoid resetting the subdevs' configuration 105 when the last configuration steps at the video node is performed. 106 107 For full sub-device control support (subdevs configured at user space before 108 starting streaming): 109 110 .. code-block:: none 111 112 # echo "sub-dev" > /sys/platform/devices/s5p-fimc-md/subdev_conf_mode 113 114 For V4L2 video node control only (subdevs configured internally by the host 115 driver): 116 117 .. code-block:: none 118 119 # echo "vid-dev" > /sys/platform/devices/s5p-fimc-md/subdev_conf_mode 120 121 This is a default option. 122 123 5. Device mapping to video and subdev device nodes 124 -------------------------------------------------- 125 126 There are associated two video device nodes with each device instance in 127 hardware - video capture and mem-to-mem and additionally a subdev node for 128 more precise FIMC capture subsystem control. In addition a separate v4l2 129 sub-device node is created per each MIPI-CSIS device. 130 131 How to find out which /dev/video? or /dev/v4l-subdev? is assigned to which 132 device? 133 134 You can either grep through the kernel log to find relevant information, i.e. 135 136 .. code-block:: none 137 138 # dmesg | grep -i fimc 139 140 (note that udev, if present, might still have rearranged the video nodes), 141 142 or retrieve the information from /dev/media? with help of the media-ctl tool: 143 144 .. code-block:: none 145 146 # media-ctl -p 147 148 7. Build 149 -------- 150 151 If the driver is built as a loadable kernel module (CONFIG_VIDEO_SAMSUNG_S5P_FIMC=m) 152 two modules are created (in addition to the core v4l2 modules): s5p-fimc.ko and 153 optional s5p-csis.ko (MIPI-CSI receiver subdev).
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