About
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This repository hosts the drivers for the Imagination Video Accelerator IPs that can be found on
Texas Instrument's J721e SoC. To learn more about these drivers, please visit the [Multimedia
Video Codec](https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-jacinto7/10_01_00_04/exports/docs/linux/Foundational_Components_Multimedia_D5520_VXE384.html) section of the SDK Documentation.

License
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You may use, distribute and copy this software under the terms of the GNU General Public License version 2.  The full GNU General Public
License version 2 can be found in the file "GPL-COPYING".

Building
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To build these drivers, there must first be a working kernel build already present on the host machine.
Instructions for this can be found in the [SDK documentation](https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-jacinto7/10_01_00_04/exports/docs/linux/Foundational_Components_Kernel_Users_Guide.html#overview) as well. 


This driver is only being tested against Texas Instruments' [Linux Kernel](https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/) using the ti-linux-6.12.y branch. Texas Instruments does not guarentee that this build will work with other Kernels.


Once a clean kernel build is done, clone this repository. Please keep in mind the directory in which the repository is cloned will be reffered to as `workdir`. `cd` into the cloned repository now and export the following enviornment variables: 


```
export ARCH=arm64
export COMPILER_PATH=<path_to_cross_compiler>
export CROSS_COMPILE=$COMPILER_PATH/aarch64-none-linux-gnu-
```

The compiler **must** be the same one being used to compile the kernel, or else the kernel build
system will complain and module building will fail. 


At this point, the following command can be run to build the modules.


`make KERNEL_DIR=<kernel_location>`

This command will generate two kernel modules files: vxe-enc.ko and vxd-dec.ko

Now that a clean kernel build is done and these external module files are generated, everything can be installed to the SD card. First, install all the kernel modules that were built during the clean build and update the kernel Image file found on SD card. This is important because the external modules will not be able to probe if the new modules and Image don't match with what the external modules were built against. Once installed, change directories back to where img-vxe-vxd repository was cloned and exectute:

`make KERNEL_DIR=<kernel_location> INSTALL_MOD_PATH=<path_to_installation> modules_install`

After this step, external modules will be found under `<install_path>/lib/modules/<kernel_version>/updates/`. This is the standard path for all out-of-tree modules.