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|
Using AVIRT
===================================
## Introduction
## Table of Contents
1. [Load/Unload AVIRT](#un-load-avirt)
2. [Configuring AVIRT](#configuring-avirt)
3. [Checking AVIRT](#checking-avirt)
<a name="un-load-avirt"/>
## 1. Loading and Unloading AVIRT
### Load Out of Tree
As root, load the required `avirt_core.ko` and subsequent audio path.
As an example, the Dummy Audiopath is being loaded here.
```sh
insmod snd-avirt-core.ko
insmod dummy/snd-avirt-ap-dummy.ko
insmod loopback/snd-avirt-ap-loopback.ko
```
### Note:
The loading and unloading of drivers can be performed using the helper scripts.
To run, we must load the kernel modules using the `scripts/load.sh` script:
```sh
$ ./scripts/load.sh
```
To unload the drivers use:
```sh
$ ./scripts/unload.sh
```
### Load In Tree
#### Note:
Either build the module in tree, or you can copy the modules manually and then run `depmod` to generate dependencies.
For example, in AGL:
```sh
mkdir -p /lib/modules/$(uname -r)/extra
cp snd-avirt-core.ko snd-avirt-ap-dummy.ko snd-avirt-ap-loopback.ko /lib/modules/$(uname -r)/extra
depmod
```
Once the modules are in place, we can load the modules using:
```sh
modprobe snd-avirt-core
modprobe snd-avirt-ap-dummy
modprobe snd-avirt-ap-loopback
```
<a name="configure-avirt" />
## 2. Configuring AVIRT
AVIRT is configured using configfs.
### Note:
A sample script for the following is supplied inside the `scripts` folder.
First, verify the kernel supports the use of configfs.
```sh
fgrep configfs /proc/filesystems
```
The expected output is:
```
nodev configfs
```
Once confirmed, we can mount the `configfs` filesystem at the conventional point:
```sh
# Check configfs is mounted on the system
mkdir -p /config
mount -t configfs none /config
```
Finally, we can configure AVIRT, for example:
```sh
# Set up each of the cards channels
mkdir /config/snd-avirt/streams/playback_media
echo "2">/config/snd-avirt/streams/playback_media/channels
echo "ap_dummy">/config/snd-avirt/streams/playback_media/map
mkdir /config/snd-avirt/streams/playback_navigation
echo "1">/config/snd-avirt/streams/playback_navigation/channels
echo "ap_dummy">/config/snd-avirt/streams/playback_navigation/map
mkdir /config/snd-avirt/streams/playback_emergency
echo "1">/config/snd-avirt/streams/playback_emergency/channels
echo "ap_dummy">/config/snd-avirt/streams/playback_emergency/map
mkdir /config/snd-avirt/streams/capture_voice
echo "1">/config/snd-avirt/streams/capture_voice/channels
echo "ap_dummy">/config/snd-avirt/streams/capture_voice/map
# Finally, seal the card, and initiate configuration
echo "1">/config/snd-avirt/streams/sealed
```
Alternatively, the test script at `scripts/test_configfs.sh` can be used.
The user-space library, [libavirt](https://github.com/fiberdyne/libavirt) can be used to interact with the configfs interface. Please refer to the README in libavirt for further details.
<a name="checking-avirt" />
## 3. Checking AVIRT Loaded Correctly
We can see the newly created streams by using the `aplay` utility. For example, the device list might look a little like this:
```sh
aplay -l
...
card 2: avirt [avirt], device 0: multimedia [multimedia]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: avirt [avirt], device 1: navigation [navigation]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: avirt [avirt], device 2: emergency [emergency]
Subdevices: 1/1
Subdevice #0: subdevice #0
...
```
|
