mirror of
https://github.com/torvalds/linux.git
synced 2024-11-21 19:41:42 +00:00
72ad4ff638
Due to recent changes on the way we're maintaining media, the location of the main tree was updated. Change docs accordingly. Cc: stable@vger.kernel.org Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
358 lines
12 KiB
ReStructuredText
358 lines
12 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
===================================
|
|
Building support for a media device
|
|
===================================
|
|
|
|
The first step is to download the Kernel's source code, either via a
|
|
distribution-specific source file or via the Kernel's main git tree\ [1]_.
|
|
|
|
Please notice, however, that, if:
|
|
|
|
- you're a braveheart and want to experiment with new stuff;
|
|
- if you want to report a bug;
|
|
- if you're developing new patches
|
|
|
|
you should use the main media development tree ``master`` branch:
|
|
|
|
https://git.linuxtv.org/media.git/
|
|
|
|
In this case, you may find some useful information at the
|
|
`LinuxTv wiki pages <https://linuxtv.org/wiki>`_:
|
|
|
|
https://linuxtv.org/wiki/index.php/How_to_Obtain,_Build_and_Install_V4L-DVB_Device_Drivers
|
|
|
|
.. [1] The upstream Linux Kernel development tree is located at
|
|
|
|
https://git.kernel.org/pub/scm/li nux/kernel/git/torvalds/linux.git/
|
|
|
|
Configuring the Linux Kernel
|
|
============================
|
|
|
|
You can access a menu of Kernel building options with::
|
|
|
|
$ make menuconfig
|
|
|
|
Then, select all desired options and exit it, saving the configuration.
|
|
|
|
The changed configuration will be at the ``.config`` file. It would
|
|
look like::
|
|
|
|
...
|
|
# CONFIG_RC_CORE is not set
|
|
# CONFIG_CEC_CORE is not set
|
|
CONFIG_MEDIA_SUPPORT=m
|
|
CONFIG_MEDIA_SUPPORT_FILTER=y
|
|
...
|
|
|
|
The media subsystem is controlled by those menu configuration options::
|
|
|
|
Device Drivers --->
|
|
<M> Remote Controller support --->
|
|
[ ] HDMI CEC RC integration
|
|
[ ] Enable CEC error injection support
|
|
[*] HDMI CEC drivers --->
|
|
<*> Multimedia support --->
|
|
|
|
The ``Remote Controller support`` option enables the core support for
|
|
remote controllers\ [2]_.
|
|
|
|
The ``HDMI CEC RC integration`` option enables integration of HDMI CEC
|
|
with Linux, allowing to receive data via HDMI CEC as if it were produced
|
|
by a remote controller directly connected to the machine.
|
|
|
|
The ``HDMI CEC drivers`` option allow selecting platform and USB drivers
|
|
that receives and/or transmits CEC codes via HDMI interfaces\ [3]_.
|
|
|
|
The last option (``Multimedia support``) enables support for cameras,
|
|
audio/video grabbers and TV.
|
|
|
|
The media subsystem support can either be built together with the main
|
|
Kernel or as a module. For most use cases, it is preferred to have it
|
|
built as modules.
|
|
|
|
.. note::
|
|
|
|
Instead of using a menu, the Kernel provides a script with allows
|
|
enabling configuration options directly. To enable media support
|
|
and remote controller support using Kernel modules, you could use::
|
|
|
|
$ scripts/config -m RC_CORE
|
|
$ scripts/config -m MEDIA_SUPPORT
|
|
|
|
.. [2] ``Remote Controller support`` should also be enabled if you
|
|
want to use some TV card drivers that may depend on the remote
|
|
controller core support.
|
|
|
|
.. [3] Please notice that the DRM subsystem also have drivers for GPUs
|
|
that use the media HDMI CEC support.
|
|
|
|
Those GPU-specific drivers are selected via the ``Graphics support``
|
|
menu, under ``Device Drivers``.
|
|
|
|
When a GPU driver supports HDMI CEC, it will automatically
|
|
enable the CEC core support at the media subsystem.
|
|
|
|
Media dependencies
|
|
------------------
|
|
|
|
It should be noticed that enabling the above from a clean config is
|
|
usually not enough. The media subsystem depends on several other Linux
|
|
core support in order to work.
|
|
|
|
For example, most media devices use a serial communication bus in
|
|
order to talk with some peripherals. Such bus is called I²C
|
|
(Inter-Integrated Circuit). In order to be able to build support
|
|
for such hardware, the I²C bus support should be enabled, either via
|
|
menu or with::
|
|
|
|
./scripts/config -m I2C
|
|
|
|
Another example: the remote controller core requires support for
|
|
input devices, with can be enabled with::
|
|
|
|
./scripts/config -m INPUT
|
|
|
|
Other core functionality may also be needed (like PCI and/or USB support),
|
|
depending on the specific driver(s) you would like to enable.
|
|
|
|
Enabling Remote Controller Support
|
|
----------------------------------
|
|
|
|
The remote controller menu allows selecting drivers for specific devices.
|
|
It's menu looks like this::
|
|
|
|
--- Remote Controller support
|
|
<M> Compile Remote Controller keymap modules
|
|
[*] LIRC user interface
|
|
[*] Support for eBPF programs attached to lirc devices
|
|
[*] Remote controller decoders --->
|
|
[*] Remote Controller devices --->
|
|
|
|
The ``Compile Remote Controller keymap modules`` option creates key maps for
|
|
several popular remote controllers.
|
|
|
|
The ``LIRC user interface`` option adds enhanced functionality when using the
|
|
``lirc`` program, by enabling an API that allows userspace to receive raw data
|
|
from remote controllers.
|
|
|
|
The ``Support for eBPF programs attached to lirc devices`` option allows
|
|
the usage of special programs (called eBPF) that would allow applications
|
|
to add extra remote controller decoding functionality to the Linux Kernel.
|
|
|
|
The ``Remote controller decoders`` option allows selecting the
|
|
protocols that will be recognized by the Linux Kernel. Except if you
|
|
want to disable some specific decoder, it is suggested to keep all
|
|
sub-options enabled.
|
|
|
|
The ``Remote Controller devices`` allows you to select the drivers
|
|
that would be needed to support your device.
|
|
|
|
The same configuration can also be set via the ``script/config``
|
|
script. So, for instance, in order to support the ITE remote controller
|
|
driver (found on Intel NUCs and on some ASUS x86 desktops), you could do::
|
|
|
|
$ scripts/config -e INPUT
|
|
$ scripts/config -e ACPI
|
|
$ scripts/config -e MODULES
|
|
$ scripts/config -m RC_CORE
|
|
$ scripts/config -e RC_DEVICES
|
|
$ scripts/config -e RC_DECODERS
|
|
$ scripts/config -m IR_RC5_DECODER
|
|
$ scripts/config -m IR_ITE_CIR
|
|
|
|
Enabling HDMI CEC Support
|
|
-------------------------
|
|
|
|
The HDMI CEC support is set automatically when a driver requires it. So,
|
|
all you need to do is to enable support either for a graphics card
|
|
that needs it or by one of the existing HDMI drivers.
|
|
|
|
The HDMI-specific drivers are available at the ``HDMI CEC drivers``
|
|
menu\ [4]_::
|
|
|
|
--- HDMI CEC drivers
|
|
< > ChromeOS EC CEC driver
|
|
< > Amlogic Meson AO CEC driver
|
|
< > Amlogic Meson G12A AO CEC driver
|
|
< > Generic GPIO-based CEC driver
|
|
< > Samsung S5P CEC driver
|
|
< > STMicroelectronics STiH4xx HDMI CEC driver
|
|
< > STMicroelectronics STM32 HDMI CEC driver
|
|
< > Tegra HDMI CEC driver
|
|
< > SECO Boards HDMI CEC driver
|
|
[ ] SECO Boards IR RC5 support
|
|
< > Pulse Eight HDMI CEC
|
|
< > RainShadow Tech HDMI CEC
|
|
|
|
.. [4] The above contents is just an example. The actual options for
|
|
HDMI devices depends on the system's architecture and may vary
|
|
on new Kernels.
|
|
|
|
Enabling Media Support
|
|
----------------------
|
|
|
|
The Media menu has a lot more options than the remote controller menu.
|
|
Once selected, you should see the following options::
|
|
|
|
--- Media support
|
|
[ ] Filter media drivers
|
|
[*] Autoselect ancillary drivers
|
|
Media device types --->
|
|
Media core support --->
|
|
Video4Linux options --->
|
|
Media controller options --->
|
|
Digital TV options --->
|
|
HDMI CEC options --->
|
|
Media drivers --->
|
|
Media ancillary drivers --->
|
|
|
|
Except if you know exactly what you're doing, or if you want to build
|
|
a driver for a SoC platform, it is strongly recommended to keep the
|
|
``Autoselect ancillary drivers`` option turned on, as it will auto-select
|
|
the needed I²C ancillary drivers.
|
|
|
|
There are now two ways to select media device drivers, as described
|
|
below.
|
|
|
|
``Filter media drivers`` menu
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
This menu is meant to easy setup for PC and Laptop hardware. It works
|
|
by letting the user to specify what kind of media drivers are desired,
|
|
with those options::
|
|
|
|
[ ] Cameras and video grabbers
|
|
[ ] Analog TV
|
|
[ ] Digital TV
|
|
[ ] AM/FM radio receivers/transmitters
|
|
[ ] Software defined radio
|
|
[ ] Platform-specific devices
|
|
[ ] Test drivers
|
|
|
|
So, if you want to add support to a camera or video grabber only,
|
|
select just the first option. Multiple options are allowed.
|
|
|
|
Once the options on this menu are selected, the building system will
|
|
auto-select the needed core drivers in order to support the selected
|
|
functionality.
|
|
|
|
.. note::
|
|
|
|
Most TV cards are hybrid: they support both Analog TV and Digital TV.
|
|
|
|
If you have an hybrid card, you may need to enable both ``Analog TV``
|
|
and ``Digital TV`` at the menu.
|
|
|
|
When using this option, the defaults for the media support core
|
|
functionality are usually good enough to provide the basic functionality
|
|
for the driver. Yet, you could manually enable some desired extra (optional)
|
|
functionality using the settings under each of the following
|
|
``Media support`` sub-menus::
|
|
|
|
Media core support --->
|
|
Video4Linux options --->
|
|
Media controller options --->
|
|
Digital TV options --->
|
|
HDMI CEC options --->
|
|
|
|
Once you select the desired filters, the drivers that matches the filtering
|
|
criteria will be available at the ``Media support->Media drivers`` sub-menu.
|
|
|
|
``Media Core Support`` menu without filtering
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
If you disable the ``Filter media drivers`` menu, all drivers available
|
|
for your system whose dependencies are met should be shown at the
|
|
``Media drivers`` menu.
|
|
|
|
Please notice, however, that you should first ensure that the
|
|
``Media Core Support`` menu has all the core functionality your drivers
|
|
would need, as otherwise the corresponding device drivers won't be shown.
|
|
|
|
Example
|
|
-------
|
|
|
|
In order to enable modular support for one of the boards listed on
|
|
:doc:`this table <cx231xx-cardlist>`, with modular media core modules, the
|
|
``.config`` file should contain those lines::
|
|
|
|
CONFIG_MODULES=y
|
|
CONFIG_USB=y
|
|
CONFIG_I2C=y
|
|
CONFIG_INPUT=y
|
|
CONFIG_RC_CORE=m
|
|
CONFIG_MEDIA_SUPPORT=m
|
|
CONFIG_MEDIA_SUPPORT_FILTER=y
|
|
CONFIG_MEDIA_ANALOG_TV_SUPPORT=y
|
|
CONFIG_MEDIA_DIGITAL_TV_SUPPORT=y
|
|
CONFIG_MEDIA_USB_SUPPORT=y
|
|
CONFIG_VIDEO_CX231XX=y
|
|
CONFIG_VIDEO_CX231XX_DVB=y
|
|
|
|
Building and installing a new Kernel
|
|
====================================
|
|
|
|
Once the ``.config`` file has everything needed, all it takes to build
|
|
is to run the ``make`` command::
|
|
|
|
$ make
|
|
|
|
And then install the new Kernel and its modules::
|
|
|
|
$ sudo make modules_install
|
|
$ sudo make install
|
|
|
|
Building just the new media drivers and core
|
|
============================================
|
|
|
|
Running a new development Kernel from the development tree is usually risky,
|
|
because it may have experimental changes that may have bugs. So, there are
|
|
some ways to build just the new drivers, using alternative trees.
|
|
|
|
There is the `Linux Kernel backports project
|
|
<https://backports.wiki.kernel.org/index.php/Main_Page>`_, with contains
|
|
newer drivers meant to be compiled against stable Kernels.
|
|
|
|
The LinuxTV developers, with are responsible for maintaining the media
|
|
subsystem also maintains a backport tree, with just the media drivers
|
|
daily updated from the newest kernel. Such tree is available at:
|
|
|
|
https://git.linuxtv.org/media_build.git/
|
|
|
|
It should be noticed that, while it should be relatively safe to use the
|
|
``media_build`` tree for testing purposes, there are not warranties that
|
|
it would work (or even build) on a random Kernel. This tree is maintained
|
|
using a "best-efforts" principle, as time permits us to fix issues there.
|
|
|
|
If you notice anything wrong on it, feel free to submit patches at the
|
|
Linux media subsystem's mailing list: media@vger.kernel.org. Please
|
|
add ``[PATCH media-build]`` at the e-mail's subject if you submit a new
|
|
patch for the media-build.
|
|
|
|
Before using it, you should run::
|
|
|
|
$ ./build
|
|
|
|
.. note::
|
|
|
|
1) you may need to run it twice if the ``media-build`` tree gets
|
|
updated;
|
|
2) you may need to do a ``make distclean`` if you had built it
|
|
in the past for a different Kernel version than the one you're
|
|
currently using;
|
|
3) by default, it will use the same config options for media as
|
|
the ones defined on the Kernel you're running.
|
|
|
|
In order to select different drivers or different config options,
|
|
use::
|
|
|
|
$ make menuconfig
|
|
|
|
Then, you can build and install the new drivers::
|
|
|
|
$ make && sudo make install
|
|
|
|
This will override the previous media drivers that your Kernel were
|
|
using.
|