1 .. SPDX-License-Identifier: GPL-2.0
2
3 ===================================
4 Building support for a media device
5 ===================================
6
7 The first step is to download the Kernel's sou
8 distribution-specific source file or via the K
9
10 Please notice, however, that, if:
11
12 - you're a braveheart and want to experiment w
13 - if you want to report a bug;
14 - if you're developing new patches
15
16 you should use the main media development tree
17
18 https://git.linuxtv.org/media_tree.git/
19
20 In this case, you may find some useful informa
21 `LinuxTv wiki pages <https://linuxtv.org/wiki>
22
23 https://linuxtv.org/wiki/index.php/How_to_
24
25 .. [1] The upstream Linux Kernel development t
26
27 https://git.kernel.org/pub/scm/li nux/
28
29 Configuring the Linux Kernel
30 ============================
31
32 You can access a menu of Kernel building optio
33
34 $ make menuconfig
35
36 Then, select all desired options and exit it,
37
38 The changed configuration will be at the ``.co
39 look like::
40
41 ...
42 # CONFIG_RC_CORE is not set
43 # CONFIG_CEC_CORE is not set
44 CONFIG_MEDIA_SUPPORT=m
45 CONFIG_MEDIA_SUPPORT_FILTER=y
46 ...
47
48 The media subsystem is controlled by those men
49
50 Device Drivers --->
51 <M> Remote Controller support --->
52 [ ] HDMI CEC RC integration
53 [ ] Enable CEC error injection support
54 [*] HDMI CEC drivers --->
55 <*> Multimedia support --->
56
57 The ``Remote Controller support`` option enabl
58 remote controllers\ [2]_.
59
60 The ``HDMI CEC RC integration`` option enables
61 with Linux, allowing to receive data via HDMI
62 by a remote controller directly connected to t
63
64 The ``HDMI CEC drivers`` option allow selectin
65 that receives and/or transmits CEC codes via H
66
67 The last option (``Multimedia support``) enabl
68 audio/video grabbers and TV.
69
70 The media subsystem support can either be buil
71 Kernel or as a module. For most use cases, it
72 built as modules.
73
74 .. note::
75
76 Instead of using a menu, the Kernel provide
77 enabling configuration options directly. To
78 and remote controller support using Kernel
79
80 $ scripts/config -m RC_CORE
81 $ scripts/config -m MEDIA_SUPPORT
82
83 .. [2] ``Remote Controller support`` should al
84 want to use some TV card drivers that m
85 controller core support.
86
87 .. [3] Please notice that the DRM subsystem al
88 that use the media HDMI CEC support.
89
90 Those GPU-specific drivers are selected
91 menu, under ``Device Drivers``.
92
93 When a GPU driver supports HDMI CEC, it
94 enable the CEC core support at the medi
95
96 Media dependencies
97 ------------------
98
99 It should be noticed that enabling the above f
100 usually not enough. The media subsystem depend
101 core support in order to work.
102
103 For example, most media devices use a serial c
104 order to talk with some peripherals. Such bus
105 (Inter-Integrated Circuit). In order to be abl
106 for such hardware, the I²C bus support should
107 menu or with::
108
109 ./scripts/config -m I2C
110
111 Another example: the remote controller core re
112 input devices, with can be enabled with::
113
114 ./scripts/config -m INPUT
115
116 Other core functionality may also be needed (l
117 depending on the specific driver(s) you would
118
119 Enabling Remote Controller Support
120 ----------------------------------
121
122 The remote controller menu allows selecting dr
123 It's menu looks like this::
124
125 --- Remote Controller support
126 <M> Compile Remote Controller keyma
127 [*] LIRC user interface
128 [*] Support for eBPF programs att
129 [*] Remote controller decoders ---
130 [*] Remote Controller devices --->
131
132 The ``Compile Remote Controller keymap modules
133 several popular remote controllers.
134
135 The ``LIRC user interface`` option adds enhanc
136 ``lirc`` program, by enabling an API that allo
137 from remote controllers.
138
139 The ``Support for eBPF programs attached to li
140 the usage of special programs (called eBPF) th
141 to add extra remote controller decoding functi
142
143 The ``Remote controller decoders`` option allo
144 protocols that will be recognized by the Linux
145 want to disable some specific decoder, it is s
146 sub-options enabled.
147
148 The ``Remote Controller devices`` allows you t
149 that would be needed to support your device.
150
151 The same configuration can also be set via the
152 script. So, for instance, in order to support
153 driver (found on Intel NUCs and on some ASUS x
154
155 $ scripts/config -e INPUT
156 $ scripts/config -e ACPI
157 $ scripts/config -e MODULES
158 $ scripts/config -m RC_CORE
159 $ scripts/config -e RC_DEVICES
160 $ scripts/config -e RC_DECODERS
161 $ scripts/config -m IR_RC5_DECODER
162 $ scripts/config -m IR_ITE_CIR
163
164 Enabling HDMI CEC Support
165 -------------------------
166
167 The HDMI CEC support is set automatically when
168 all you need to do is to enable support either
169 that needs it or by one of the existing HDMI d
170
171 The HDMI-specific drivers are available at the
172 menu\ [4]_::
173
174 --- HDMI CEC drivers
175 < > ChromeOS EC CEC driver
176 < > Amlogic Meson AO CEC driver
177 < > Amlogic Meson G12A AO CEC driver
178 < > Generic GPIO-based CEC driver
179 < > Samsung S5P CEC driver
180 < > STMicroelectronics STiH4xx HDMI
181 < > STMicroelectronics STM32 HDMI CE
182 < > Tegra HDMI CEC driver
183 < > SECO Boards HDMI CEC driver
184 [ ] SECO Boards IR RC5 support
185 < > Pulse Eight HDMI CEC
186 < > RainShadow Tech HDMI CEC
187
188 .. [4] The above contents is just an example.
189 HDMI devices depends on the system's ar
190 on new Kernels.
191
192 Enabling Media Support
193 ----------------------
194
195 The Media menu has a lot more options than the
196 Once selected, you should see the following op
197
198 --- Media support
199 [ ] Filter media drivers
200 [*] Autoselect ancillary drivers
201 Media device types --->
202 Media core support --->
203 Video4Linux options --->
204 Media controller options --->
205 Digital TV options --->
206 HDMI CEC options --->
207 Media drivers --->
208 Media ancillary drivers --->
209
210 Except if you know exactly what you're doing,
211 a driver for a SoC platform, it is strongly re
212 ``Autoselect ancillary drivers`` option turned
213 the needed I²C ancillary drivers.
214
215 There are now two ways to select media device
216 below.
217
218 ``Filter media drivers`` menu
219 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
220
221 This menu is meant to easy setup for PC and La
222 by letting the user to specify what kind of me
223 with those options::
224
225 [ ] Cameras and video grabbers
226 [ ] Analog TV
227 [ ] Digital TV
228 [ ] AM/FM radio receivers/transmitters
229 [ ] Software defined radio
230 [ ] Platform-specific devices
231 [ ] Test drivers
232
233 So, if you want to add support to a camera or
234 select just the first option. Multiple options
235
236 Once the options on this menu are selected, th
237 auto-select the needed core drivers in order t
238 functionality.
239
240 .. note::
241
242 Most TV cards are hybrid: they support both
243
244 If you have an hybrid card, you may need to
245 and ``Digital TV`` at the menu.
246
247 When using this option, the defaults for the m
248 functionality are usually good enough to provi
249 for the driver. Yet, you could manually enable
250 functionality using the settings under each of
251 ``Media support`` sub-menus::
252
253 Media core support --->
254 Video4Linux options --->
255 Media controller options --->
256 Digital TV options --->
257 HDMI CEC options --->
258
259 Once you select the desired filters, the drive
260 criteria will be available at the ``Media supp
261
262 ``Media Core Support`` menu without filtering
263 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
264
265 If you disable the ``Filter media drivers`` me
266 for your system whose dependencies are met sho
267 ``Media drivers`` menu.
268
269 Please notice, however, that you should first
270 ``Media Core Support`` menu has all the core f
271 would need, as otherwise the corresponding dev
272
273 Example
274 -------
275
276 In order to enable modular support for one of
277 :doc:`this table <cx231xx-cardlist>`, with mod
278 ``.config`` file should contain those lines::
279
280 CONFIG_MODULES=y
281 CONFIG_USB=y
282 CONFIG_I2C=y
283 CONFIG_INPUT=y
284 CONFIG_RC_CORE=m
285 CONFIG_MEDIA_SUPPORT=m
286 CONFIG_MEDIA_SUPPORT_FILTER=y
287 CONFIG_MEDIA_ANALOG_TV_SUPPORT=y
288 CONFIG_MEDIA_DIGITAL_TV_SUPPORT=y
289 CONFIG_MEDIA_USB_SUPPORT=y
290 CONFIG_VIDEO_CX231XX=y
291 CONFIG_VIDEO_CX231XX_DVB=y
292
293 Building and installing a new Kernel
294 ====================================
295
296 Once the ``.config`` file has everything neede
297 is to run the ``make`` command::
298
299 $ make
300
301 And then install the new Kernel and its module
302
303 $ sudo make modules_install
304 $ sudo make install
305
306 Building just the new media drivers and core
307 ============================================
308
309 Running a new development Kernel from the deve
310 because it may have experimental changes that
311 some ways to build just the new drivers, using
312
313 There is the `Linux Kernel backports project
314 <https://backports.wiki.kernel.org/index.php/M
315 newer drivers meant to be compiled against sta
316
317 The LinuxTV developers, with are responsible f
318 subsystem also maintains a backport tree, with
319 daily updated from the newest kernel. Such tre
320
321 https://git.linuxtv.org/media_build.git/
322
323 It should be noticed that, while it should be
324 ``media_build`` tree for testing purposes, the
325 it would work (or even build) on a random Kern
326 using a "best-efforts" principle, as time perm
327
328 If you notice anything wrong on it, feel free
329 Linux media subsystem's mailing list: media@vg
330 add ``[PATCH media-build]`` at the e-mail's su
331 patch for the media-build.
332
333 Before using it, you should run::
334
335 $ ./build
336
337 .. note::
338
339 1) you may need to run it twice if the ``m
340 updated;
341 2) you may need to do a ``make distclean``
342 in the past for a different Kernel vers
343 currently using;
344 3) by default, it will use the same config
345 the ones defined on the Kernel you're r
346
347 In order to select different drivers or differ
348 use::
349
350 $ make menuconfig
351
352 Then, you can build and install the new driver
353
354 $ make && sudo make install
355
356 This will override the previous media drivers
357 using.
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