The cardlist section is important for some boards, because they may require extra modprobe parameters. Improve the docs to mention that. Thanks-to: Hans Verkuil <hverkuil-cisco@xxxxxxxxx> # for providing me some PCI IDs Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> --- Documentation/admin-guide/media/cardlist.rst | 116 ++++++++++++++++++- 1 file changed, 111 insertions(+), 5 deletions(-) diff --git a/Documentation/admin-guide/media/cardlist.rst b/Documentation/admin-guide/media/cardlist.rst index 527188ee9697..025d251764c2 100644 --- a/Documentation/admin-guide/media/cardlist.rst +++ b/Documentation/admin-guide/media/cardlist.rst @@ -1,22 +1,128 @@ .. SPDX-License-Identifier: GPL-2.0 +========== Cards List ========== +The media subsystem provide support for lots of PCI and USB drivers, plus +platform-specific drivers. It also contains several ancillary I²C drivers. + +The platform-specific drivers are usually present on embedded systems, +or are supported by the main board. Usually, setting them is done via +OpenFirmware or ACPI. + +The PCI and USB drivers, however, are independent of the system's board, +and may be added/removed by the user. + +This section contains a list of supported PCI and USB boards. + +Please notice that this list is not exaustive. + +USB drivers +=========== + +The USB boards are identified by an identification called USB ID. + +The ``lsusb`` command allows identifying the USB IDs:: + + $ lsusb + ... + Bus 001 Device 015: ID 046d:082d Logitech, Inc. HD Pro Webcam C920 + Bus 001 Device 074: ID 2040:b131 Hauppauge + Bus 001 Device 075: ID 2013:024f PCTV Systems nanoStick T2 290e + ... + +Newer camera devices use a standard way to expose themselves as such, +via USB Video Class. Those cameras are automatically supported by the +``uvc-driver``. + +Older cameras and TV USB devices uses USB Vendor Classes: each vendor +defines its own way to access the device. This section contains +card lists for such vendor-class devices. + +While this is not as common as on PCI, sometimes the same USB ID is used +by different products. So, several media drivers allow passing a ``card=`` +parameter, in order to setup a card number that would match the correct +settings for an specific product type. + .. toctree:: :maxdepth: 1 au0828-cardlist + cx231xx-cardlist + em28xx-cardlist + tm6000-cardlist + usbvision-cardlist + gspca-cardlist + +PCI drivers +=========== + +The PCI boards are identified by an identification called PCI ID. The PCI ID +is actually composed by two parts: + + - Vendor ID and device ID; + - Subsystem ID and Subsystem device ID; + +The ``lspci -nn`` command allows identifying the vendor/device PCI IDs:: + + $ lspci -nn + ... + 00:0b.0 Multimedia controller [0480]: Brooktree Corporation Bt878 Audio Capture [109e:0878] (rev 11) + 01:00.0 Multimedia video controller [0400]: Conexant Systems, Inc. CX23887/8 PCIe Broadcast Audio and Video Decoder with 3D Comb [14f1:8880] (rev 0f) + 01:01.0 Multimedia controller [0480]: Philips Semiconductors SAA7131/SAA7133/SAA7135 Video Broadcast Decoder [1131:7133] (rev d1) + 02:01.0 Multimedia video controller [0400]: Internext Compression Inc iTVC15 (CX23415) Video Decoder [4444:0803] (rev 01) + 02:02.0 Multimedia video controller [0400]: Conexant Systems, Inc. CX23418 Single-Chip MPEG-2 Encoder with Integrated Analog Video/Broadcast Audio Decoder [14f1:5b7a] + 02:03.0 Multimedia video controller [0400]: Brooktree Corporation Bt878 Video Capture [109e:036e] (rev 11) + ... + +The subsystem IDs can be obtained using ``lspci -vn`` + +.. code-block:: none + :emphasize-lines: 4 + + $ lspci -vn + ... + 01:01.0 0480: 1131:7133 (rev d1) + Subsystem: 1461:f01d + Flags: bus master, medium devsel, latency 32, IRQ 209 + Memory at e2002000 (32-bit, non-prefetchable) [size=2K] + Capabilities: [40] Power Management version 2 + ... + +Unfortunately, sometimes the same PCI ID is used by different products. +So, several media drivers allow passing a ``card=`` parameter, in order +to setup a card number that would match the correct settings for an +specific board. + +.. toctree:: + :maxdepth: 1 + bttv-cardlist cx18-cardlist - cx231xx-cardlist cx23885-cardlist cx88-cardlist - em28xx-cardlist ivtv-cardlist saa7134-cardlist saa7164-cardlist - tm6000-cardlist + +I²C drivers +=========== + +The I²C (Inter-Integrated Circuit) bus is a three-wires bus used internally +at the media cards for communication between different chips. While the bus +is not visible to the Linux Kernel, drivers need to send and receive +commands via the bus. The Linux Kernel driver abstraction has support to +implement different drivers for each component inside an I²C bus, as if +the bus were visible to the main system board. + +One of the problems with I²C devices is that sometimes the same device may +work with different I²C hardware. This is common, for example, on devices +that comes with a tuner for North America market, and another one for +Europe. Some drivers have a ``tuner=`` modprobe parameter to allow using a +different tuner number in order to address such issue. + +.. toctree:: + :maxdepth: 1 + tuner-cardlist - usbvision-cardlist - gspca-cardlist -- 2.25.2
