View source for STK1160-howto-linux-sunxi-3 4


<br/>
STK1160 is the new kernel driver for Easycap like USB AV capture devices.<br/>
It is available in the linux kernel from version 3.7 and above, but linux-sunxi <br/>
stable kernel is 3.4 . So this driver does not exist native in that kernel.

__TOC__

== Why use stk1160 instead of the old driver easycap ? ==
<br/>
One main reason: You can change input channel on your device.<br/>

If you have the single channel version you also have and a S-video input. But<br/>
with easycap driver you can't switch to that input. The input selection is not<br/>
supported by the easycap driver and you will be always on default input 0.

If you have the four channel version you have four AV channels and most likely<br/>
you will want to be able to switch between channels. Again old easycap driver<br/>
does not have that functionality.

NB: If you don't need changing the input channel you can use the old easycap<br/>
driver and there is one benefit: easycap supports two framerate modes: 5 and 25<br/>
fps by selecting the proper norm. For example there is norm PAL_BGHN and norm<br/>
PAL_BGHN_SLOW, which is the 5 fps mode. And on SBCs this framelimit relieve the<br/>
CPU a little bit as the capture streams only five frames per second. The stk1160<br/>
supports currently only 25 fps mode.

== What do You need before starting ==
<br/>
Kernel source.<br/>
Config file from your current kernel.<br/>
Compiler for the cross compilation.<br/>

=== Getting the kernel source ===
<br/>
For the latest stable linux-sunxi 3.4.xx kernel the command is:

<code>
git clone -b sunxi-3.4 --depth 1 https://github.com/linux-sunxi/linux-sunxi.git
</code>

Wait for the download process to finish.

=== Getting the config file from your current kernel ===
<br/>
While on the device copy the /proc/config.gz to your build machine,<br/>
then use gunzip to extract and you now have your current kernel config.

=== Getting compiler for the cross compilation ===
<br/>
On Debian add to your /etc/apt/sources.list

<code>
deb http://www.emdebian.org/debian unstable main
</code>

then

<code>
apt-get update<br/>
apt-get install gcc-4.7-arm-linux-gnueabihf
</code>

Now you have compiler for the cross compilation.

== Compiling stk1160 ==
<br/>
The stk1160 will be build using backported version provided by media_build, more<br/>
info about media_build you can find at the following link:

http://www.linuxtv.org/wiki/index.php/How_to_Obtain,_Build_and_Install_V4L-DVB_Device_Drivers

But for this to work you need to build a new kernel with V4L support as modules,<br/>
so you can load the new V4L core from media_build and also patch dma-buf.c/.h in<br/>
the kernel tree, because of a missing function there.

Lets get to work ...

Will assume that you have your kernel source tree in ~/linux-sunxi, also that<br/>
you have already copied your current kernel config like ~/linux-sunxi/.config .

=== Preparing the build environment ===
<br/>
<code>
export CROSS_COMPILE=arm-linux-gnueabihf-<br/>
export ARCH=arm
</code>

=== Patching the kernel tree: ===
<br/>
The patch is available at:

https://drive.google.com/file/d/0B6S44jnEBxzyQVhUNDFlQ2RnRUU/edit?usp=sharing

Download and execute the following commands:

<code>
cd ~/linux-sunxi<br/>
patch -p0 < /path/to/dma-buf-vmap.patch
</code>

=== Building the new kernel with V4L core as modules ===
<br/>
<code>
make silentoldconfig<br/>
make menuconfig
</code>

Go to Device Drivers -> Multimedia support and mark Video for Linux with m.
Exit and choose to save the changes to the config.
Based on your build machine use -j with value #threads your CPU is capable,
example values: dual-core no HT -j2, dual-core with HT -j4 and so on.

<code>
make -j4 uImage<br/>
make -j4 INSTALL_MOD_PATH=out modules<br/>
make -j4 INSTALL_MOD_PATH=out modules_install
</code>

The uImage file is located in linux-sunxi/arch/arm/boot/
The kernel modules are located in linux-sunxi/out/lib/modules/3.x.xx+

'''Do not rush to update your kernel and modules on your sd-card or nand.'''

=== Building media_build ===
<br/>
Download this patch for media_build:

https://drive.google.com/file/d/0B6S44jnEBxzydGlELXl4S3I2dzg/edit?usp=sharing

First we will go up one level to home dir as we were in ~/linux-sunxi, then<br/>
get latest media_build source and build it.

<code>
cd ..<br/>
git clone --depth=1 git://linuxtv.org/media_build.git<br/>
cd media_build<br/>
./build --check<br/>
</code>

Install missing packages showed from ./build --check and then continue<br/>

<code>
patch -p1 < /path/to/media_build-makefilepl.patch<br/>
make download<br/>
make untar<br/>
make prepare<br/>
DIR=~/linux-sunxi make release<br/>
nano v4l/Makefile
</code>

find and comment out the line

<code>
-include $(obj)/Makefile.sound
</code>

because sound modules require PCI support, which sunxi doesn't have

<code>
nano v4l/.version
</code>

append to the lines starting with

<code>
SUBLEVEL:=...<br/>
KERNELRELEASE:=...
</code>

one plus sign at the end as the kernel versions of linux-sunxi 3.4 stable are<br/>
in format 3.4.xx+ , but media_build for some reason omits the + .

<code>
mv v4l/.config v4l/.config.orig<br/>
nano v4l/.config
</code>

Insert the following:

<code>
CONFIG_VIDEO_DEV=m<br/>
CONFIG_VIDEO_V4L2_COMMON=m<br/>
CONFIG_VIDEO_MEDIA=m<br/>
CONFIG_VIDEO_V4L2=m<br/>
CONFIG_VIDEOBUF_GEN=m<br/>
CONFIG_VIDEOBUF_DMA_CONTIG=m<br/>
CONFIG_DMA_SHARED_BUFFER=m<br/>
CONFIG_VIDEOBUF2_CORE=m<br/>
CONFIG_VIDEOBUF2_MEMOPS=m<br/>
CONFIG_VIDEOBUF2_VMALLOC=m<br/>
CONFIG_VIDEO_CAPTURE_DRIVERS=y<br/>
CONFIG_V4L_MEM2MEM_DRIVERS=y<br/>
CONFIG_V4L_PLATFORM_DRIVERS=y<br/>
CONFIG_VIDEO_SAA711X=m<br/>
CONFIG_VIDEO_STK1160_AC97=n<br/>
CONFIG_VIDEO_STK1160=m<br/>
CONFIG_VIDEO_STK1160_COMMON=m
</code>

Save and exit. This is a stripped media_build configuration for stk1160 only.<br/>
'''NB: For audio support for your capture change CONFIG_VIDEO_STK1160_AC97 to y.'''

<code>
make -j4<br/>
DESTDIR=~/linux-sunxi/out make install
</code>

== Installing the new kernel and modules ==
<br/>
Now you have the kernel and updated modules with the new V4L core and stk1160.<br/>
Copy from ~/linux-sunxi/arch/arm/boot/uImage to your /boot folder on the device.<br/>
Then copy the modules folder /linux-sunxi/out/lib/modules/3.x.xx+ to the device.

'''Blacklisting the old easycap driver:'''<br/>
While on the device create /etc/modprobe.d/easycap-blacklist.conf and add:

<code>
blacklist easycap
</code>

Save and exit

Reboot the device and all should be ok.

== Testing ==
<br/>
Insert the capture, check with lsmod for stk1160, check dmesg for any warnings,<br/>
errors, unresolved symbols, etc, there should be none. Check if video device was<br/>
created under /dev/video0 or /dev/videoX if you have more than one V4L device.<br/>

'''PAL norm is at number 5, by default stk1160 is configured for NTSC.'''<br/>

== Known issues ==
<br/>
Sometimes you can see in dmesg warning from videobuf2-core.c, but this does not<br/>
effect the capturing or streaming. I have not found the reason for the warning,<br/>
but as it is not problematic I have left it for now.<br/>

'''Good luck and happy capturing using stk1160 :-)'''