View source for Lontium LT9211 Linux driver for Jetson

<seo title="Lontium LT9211 | LT9211 Linux Driver for Jetson" titlemode="replace" metakeywords="GStreamer, NVIDIA, LT9211, Lontium LT9211, Lontium LT9211 Linux driver, Lontium, BT656" metadescription="Learn more about the Lontium LT9211 Linux driver for Jetson which is capable of handling BT656 video data."></seo>

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== Lontium LT9211 TTL Interface Bridge features == 
Reference: [http://www.lontiumsemi.com/uploadfiles/pdf/LT9211_Brief_R1.0.pdf Lontium LT9211 bridge chip]

The Lontium LT9211 is a high performance convertor which interconvertible between MIPI DSI/CSI-2/Dual-Port LVDS and TTL except for 24bit TTL to 24bit TTL with both SYNC and DE.

* Tested resolutions are BT656. The tested format is YUV422.

* The LT9211 driver supports 2 lane configuration for the given resolution.

==Build kernel using Jetpack and LT9211 driver==

=== <u>Jetson Nano</u> ===
==== Building kernel sources ====
Follow the instructions in [[NVIDIA_Jetson_Nano_-_Building_the_Kernel_from_Source | NVIDIA_Jetson_Nano - Building the Kernel from Source]] to build the kernel sources for the Jetson Nano.

==== Enable driver ====
Once you are following the guide there is a step '''make menuconfig''', which allows you to enable the lt9211 driver as built-in. 

<syntaxhighlight lang=bash>
make ARCH=arm64 O=$KERNEL_OUT menuconfig
</syntaxhighlight>

Select the driver. The menu option is located:

<pre class="config">
-> Device Drivers
  -> Multimedia support (MEDIA_SUPPORT [=y])
    -> NVIDIA overlay Encoders, decoders, sensors and other helper chips
       <*> LT9211 camera support
</pre>

== Test your Kernel image using Jetpack root file system==

Check the kernel version. At this moment you can test the image created in order to see the new kernel is working correctly. You have to see a new kernel version with the correct date of compilation:

===<u>Jetson Nano</u>===
<syntaxhighlight lang=bash>
uname -a 
Linux nvidia 4.9.140 #6 SMP PREEMPT Tue May 7 16:25:38 CST 2019 aarch64 aarch64 aarch64 GNU/Linux
</syntaxhighlight>

==== Nano EVM kit ====

You can see that the driver is probed, execute the line:  dmesg | grep "lt9211"

Expected output:
<syntaxhighlight lang=bash>
nvidia@nvidia:~$ dmesg | grep "lt9211"
[   16.910750] lt9211 6-002d: LT9211 module found
</syntaxhighlight>

video devices created:

<syntaxhighlight lang=bash>
ls /dev/video*
/dev/video0 
</syntaxhighlight>

==Examples==

===<u>GStreamer : Jetson Nano</u>===
====BT656====
<syntaxhighlight lang=bash>
gst-launch-1.0 v4l2src num-buffers=10 ! "video/x-raw(format:Interlaced),format=UYVY,width=720,height=288,framerate=(fraction)30/1,interlace-mode=(string)alternate" ! deinterlace ! "video/x-raw,format=UYVY,width=720,height=576" ! filesink location=~/frames.raw
</syntaxhighlight>

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[[Category:Jetson]][[Category:Jetson V4L2 Drivers]][[Category:Lontium]]