| .. SPDX-License-Identifier: GPL-2.0 |
| |
| .. include:: <isonum.txt> |
| |
| The Samsung S5P/Exynos4 FIMC driver |
| =================================== |
| |
| Copyright |copy| 2012 - 2013 Samsung Electronics Co., Ltd. |
| |
| The FIMC (Fully Interactive Mobile Camera) device available in Samsung |
| SoC Application Processors is an integrated camera host interface, color |
| space converter, image resizer and rotator. It's also capable of capturing |
| data from LCD controller (FIMD) through the SoC internal writeback data |
| path. There are multiple FIMC instances in the SoCs (up to 4), having |
| slightly different capabilities, like pixel alignment constraints, rotator |
| availability, LCD writeback support, etc. The driver is located at |
| drivers/media/platform/samsung/exynos4-is directory. |
| |
| Supported SoCs |
| -------------- |
| |
| S5PC100 (mem-to-mem only), S5PV210, Exynos4210 |
| |
| Supported features |
| ------------------ |
| |
| - camera parallel interface capture (ITU-R.BT601/565); |
| - camera serial interface capture (MIPI-CSI2); |
| - memory-to-memory processing (color space conversion, scaling, mirror |
| and rotation); |
| - dynamic pipeline re-configuration at runtime (re-attachment of any FIMC |
| instance to any parallel video input or any MIPI-CSI front-end); |
| - runtime PM and system wide suspend/resume |
| |
| Not currently supported |
| ----------------------- |
| |
| - LCD writeback input |
| - per frame clock gating (mem-to-mem) |
| |
| User space interfaces |
| --------------------- |
| |
| Media device interface |
| ~~~~~~~~~~~~~~~~~~~~~~ |
| |
| The driver supports Media Controller API as defined at :ref:`media_controller`. |
| The media device driver name is "Samsung S5P FIMC". |
| |
| The purpose of this interface is to allow changing assignment of FIMC instances |
| to the SoC peripheral camera input at runtime and optionally to control internal |
| connections of the MIPI-CSIS device(s) to the FIMC entities. |
| |
| The media device interface allows to configure the SoC for capturing image |
| data from the sensor through more than one FIMC instance (e.g. for simultaneous |
| viewfinder and still capture setup). |
| |
| Reconfiguration is done by enabling/disabling media links created by the driver |
| during initialization. The internal device topology can be easily discovered |
| through media entity and links enumeration. |
| |
| Memory-to-memory video node |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| V4L2 memory-to-memory interface at /dev/video? device node. This is standalone |
| video device, it has no media pads. However please note the mem-to-mem and |
| capture video node operation on same FIMC instance is not allowed. The driver |
| detects such cases but the applications should prevent them to avoid an |
| undefined behaviour. |
| |
| Capture video node |
| ~~~~~~~~~~~~~~~~~~ |
| |
| The driver supports V4L2 Video Capture Interface as defined at |
| :ref:`devices`. |
| |
| At the capture and mem-to-mem video nodes only the multi-planar API is |
| supported. For more details see: :ref:`planar-apis`. |
| |
| Camera capture subdevs |
| ~~~~~~~~~~~~~~~~~~~~~~ |
| |
| Each FIMC instance exports a sub-device node (/dev/v4l-subdev?), a sub-device |
| node is also created per each available and enabled at the platform level |
| MIPI-CSI receiver device (currently up to two). |
| |
| sysfs |
| ~~~~~ |
| |
| In order to enable more precise camera pipeline control through the sub-device |
| API the driver creates a sysfs entry associated with "s5p-fimc-md" platform |
| device. The entry path is: /sys/platform/devices/s5p-fimc-md/subdev_conf_mode. |
| |
| In typical use case there could be a following capture pipeline configuration: |
| sensor subdev -> mipi-csi subdev -> fimc subdev -> video node |
| |
| When we configure these devices through sub-device API at user space, the |
| configuration flow must be from left to right, and the video node is |
| configured as last one. |
| |
| When we don't use sub-device user space API the whole configuration of all |
| devices belonging to the pipeline is done at the video node driver. |
| The sysfs entry allows to instruct the capture node driver not to configure |
| the sub-devices (format, crop), to avoid resetting the subdevs' configuration |
| when the last configuration steps at the video node is performed. |
| |
| For full sub-device control support (subdevs configured at user space before |
| starting streaming): |
| |
| .. code-block:: none |
| |
| # echo "sub-dev" > /sys/platform/devices/s5p-fimc-md/subdev_conf_mode |
| |
| For V4L2 video node control only (subdevs configured internally by the host |
| driver): |
| |
| .. code-block:: none |
| |
| # echo "vid-dev" > /sys/platform/devices/s5p-fimc-md/subdev_conf_mode |
| |
| This is a default option. |
| |
| 5. Device mapping to video and subdev device nodes |
| -------------------------------------------------- |
| |
| There are associated two video device nodes with each device instance in |
| hardware - video capture and mem-to-mem and additionally a subdev node for |
| more precise FIMC capture subsystem control. In addition a separate v4l2 |
| sub-device node is created per each MIPI-CSIS device. |
| |
| How to find out which /dev/video? or /dev/v4l-subdev? is assigned to which |
| device? |
| |
| You can either grep through the kernel log to find relevant information, i.e. |
| |
| .. code-block:: none |
| |
| # dmesg | grep -i fimc |
| |
| (note that udev, if present, might still have rearranged the video nodes), |
| |
| or retrieve the information from /dev/media? with help of the media-ctl tool: |
| |
| .. code-block:: none |
| |
| # media-ctl -p |
| |
| 7. Build |
| -------- |
| |
| If the driver is built as a loadable kernel module (CONFIG_VIDEO_SAMSUNG_S5P_FIMC=m) |
| two modules are created (in addition to the core v4l2 modules): s5p-fimc.ko and |
| optional s5p-csis.ko (MIPI-CSI receiver subdev). |
