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.
DM81xx refers to both DM816x, DM814x and DM813x.
Introduction
Linux HDVPSS software stack contains drivers for controlling the video display, video capture graphics paths of the
HDVPSS.Video display and capture paths are exposed using the V4L2 user interface of Linux. Graphics path of the
HDVPSS is controlled using the frame buffer (fbdev) interface of Linux. HDVPSS hardware supports number of
different analog and digital video encoders and decoders. All of these encoders can be used to drive the external
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
HDVPSS capture in addition to the sub-device ioctls. This information is passed to V4L2 capture driver through
platform data. Following part of the document explains how to add/delete external decoders.
Design
All the external decoders are controlled through standard V4L2 driver model architecture. All the decoders need to
be implemented as V4L2 sub-device architecture. All the standard APIs that need to be supported by decoder based
on decoder features are listed in V4L2 API specification. Link to V4L2 API specification is given in references
section of this documentation.
Steps for Adding new Decoders
• All the files related to new external decoders should be added in following kernel directory
$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/
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资源评论
gqb6662013-01-17谢谢楼主分享，正在研究这一块！
