mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-25 05:04:09 +08:00
media: admin-guide: add a generic building guide
Several of the existing documents under the media admin-guide contain build procedures. Add an specific chapter describing it. This document was partially inspired on the modifications I made to the bttv.rst file. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Mauro Carvalho Chehab
parent
d9d43617bb
commit
2aca74c8b1
357
Documentation/admin-guide/media/building.rst
Normal file
357
Documentation/admin-guide/media/building.rst
Normal file
@ -0,0 +1,357 @@
|
||||
.. 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_tree.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 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 aplications
|
||||
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 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.
|
||||
@ -35,6 +35,7 @@ Video4Linux (V4L) driver-specific documentation
|
||||
:numbered:
|
||||
|
||||
intro
|
||||
building
|
||||
|
||||
cardlist
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user