DM81xx AM38xx Adding External Decoders to V4L2 Capture Driver

DM81xx AM38xx Adding External Decoders to V4L2 Capture Driver

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DM81xx AM38xx Adding External Decoders to

V4L2 Capture Driver

DM81xx AM38xx Adding External Decoders to V4L2 Capture Driver

Linux PSP

IMPORTANT

DM816x refers to DM816x/AM389x devices unless specified.

DM814x refers to DM814x/AM387x devices unless specified.

encoders which can convert output of HDVPSS encoder to any of the standard video protocols like HDMI, DVI, and

VGA etc. All of the decoders can be used to convert the incoming videos in different protocols like HDMI, DVI

VGA etc to the standard BT656, BT1120, BT601 interface which HDVPSS understands.

All the external decoders are supported with V4L2 capture driver using standard V4L2 sub-device model. Decoders

that are required to be interfaced to the V4L2 capture driver needs to adhere V4L2 sub-device architecture. More

about V4L2 sub-device architecture is available at $Kernel_source/Documentation/video4linux/v4l2-framework.txt

V4L2 master driver requires information on how the decoder driver is interfaced to V4L2 master driver that is

platform data. Following part of the document explains how to add/delete external decoders.

Design

$kernel_source/drivers/media/video/<external_decoder_directory_file>

• MakeFiles and Kconfig files needs to be modified accordingly. Please refer to following kernel documentation on

makefiles and Kconfig under following kernel directory.

$kernel_source/Documentation/kbuild/

DM81xx AM38xx Adding External Decoders to V4L2 Capture Driver

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• TVP7002 decoder is added as the sub-device model in Linux Driver stack. Please refer following files for

TVP7002 decoder implementation.

$kernel_source/drivers/media/video/tvp7002.c

$kernel_source/drivers/media/video/tvp7002_reg.h

$kernel_source/drivers/media/video/tvp7002_reg.h

$kernel_source/media/video/Makefile

• ti81xxvin_config data structure needs to be field and passed it as platform data to the HDVPSS V4L2 capture

driver. It includes many sub-structures and enums all those will be explained in sub-sequent sections in code.

Structures

All the structures that needs to be instantiate and filled in according to the external decoder and connectivity between

decoder and VIP are explained below. /* Structure to configure V4L2 capture driver based

on external decoders preset on board. */ struct ti81xxvin_config {

/* Configuration for each instance of VIP */

struct ti81xxvin_inst_config inst_config[TI81XXVIN_NUM_INSTANCES];

/* Information for all sub-devices (external decoders) connected to VIP port */

struct ti81xxvin_subdev_info *subdev_info;

they support. This structure is used by master driver to select particular decoder based on the input selected. Like

if two decoders are connected to same VIP port, than based on input selected, master driver will configured any

one of the decoder. Even same decoder can support mutiple inputs like TVP5147 supports composite as well as

s-video inputs.

/* V4L2 master driver instance configuration based on decoder connected to

specific master driver*/ struct ti81xxvin_inst_config {

/* Different inputs possible on this instance like DVI, HDMI,

* Component etc. This is addition of all the different inputs

* supported bu all the decoders connected to this V4L2 master driver instance.

*/

DM81xx AM38xx Adding External Decoders to V4L2 Capture Driver

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};

struct ti81xxvin_input {

* for details.

*/

struct v4l2_input input;

/* Sub-device name */

const char *subdev_name;

/* Different DV presets this input supports

* This is a standard V4L2 structure. Please refer to V4L2 specifications

* for details.

*/

const struct v4l2_dv_preset *dv_presets;

/* Number of presets supported by this input */

int num_dv_presets;

* What is its i2c address, sub-device name etc. This should match

* sub-device name given in the sub-device driver under driver/media/video folder.

* Based on name only sub-device will be searched.

*/

struct i2c_board_info board_info;

/* HDVPSS video input port configuration based on how sub-device is interfaced to

* the HDVPSS VIP Port

*/

struct Vps_VipPortConfig vip_port_cfg;

* For details see #Vps_CaptVideoIfMode