Matrix:Module-cs4281

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Contents

The module options for snd-cs4281

description:  Cirrus Logic CS4281
author:  Jaroslav Kysela
license: GPL
parm: index:Index value for CS4281 soundcard. (array of int)
parm: id:ID string for CS4281 soundcard. (array of charp)
parm: enable:Enable CS4281 soundcard. (array of bool)

Introduction for Crystal CS4281 soundcard

There are two ways of getting Linux drivers to work, you can either compile them into the kernel or build them separately as modules. Read the Kernel-HOWTO for details of how to compile a kernel.

You must turn on the sound support soundcore module. This is in the kernel. Look in the sound drivers directory and it should be the first option. Most people enable the module setting. That way you can load and unload the module manually if you have multiple soundcards/​devices or if you intend to debug or use cutting edge software which may cause your drivers to halt sometimes. Of course it also means you have more control of your system.

Most modern distros come with soundcore compiled as a module. You can check this in numerous ways. The easiest way is to type:

       modinfo soundcore

If this command returns that you have this module, then you don't need to recompile your kernel.

Quick installation

This explains how to build from source tarballs. See GIT_Server for instructions on getting and using the latest source from git repositories.

Type the following commands in the shell of your choice.

Make a directory to store the alsa source code in:

       cd /usr/src
       mkdir alsa
       cd alsa
       cp /downloads/alsa-* .

Now unzip and install the alsa-driver package:

       bunzip2 alsa-driver-xxx
       tar -xf alsa-driver-xxx
       cd alsa-driver-xxx
       ./configure --with-cards=cs4281 --with-sequencer=yes ; make ; make install

Now unzip and install the alsa-lib package:

       cd ..
       bunzip2 alsa-lib-xxx
       tar -xf alsa-lib-xxx
       cd alsa-lib-xxx
       ./configure ; make ; make install

Now unzip and install the alsa-firmware package:

       cd ..
       bunzip2 alsa-firmware-xxx
       tar -xf alsa-firmware-xxx
       cd alsa-firmware-xxx
       ./configure ; make ; make install

Now unzip and install the alsa-utils package:

       cd ..
       bunzip2 alsa-utils-xxx
       tar -xf alsa-utils-xxx
       cd alsa-utils-xxx
       ./configure ; make ; make install

Now insert the modules into the kernel:

       modprobe snd-cs4281 ; modprobe snd-pcm-oss ; modprobe snd-mixer-oss ; modprobe snd-seq-oss

Now adjust your soundcard's volume levels. All mixer channels are muted by default. You must use a native mixer program to unmute appropriate channels, for example alsamixer from the alsa-utils package. Note that some usb-audio devices do not have internal mixer controls. Run:

       alsamixer

You can also look at the utils/​alsasound file. This script is designed for the RedHat Linux distribution, but it can also be used with other distributions which use System V style rc init scripts. This will allow you to load your modules at boot time. If you don't want to do this you can of course compile them into the kernel instead and save yourself the hassle of coming to terms with the rc init scripts.

Setting up modprobe and kmod support

Before you send a mail complaining that "I don't have /etc/​modules.conf, where do I find it ……" ‒ the /etc/​conf.modules has been deprecated with a few distro's, but in your case it may still be /etc/​conf.modules. Basically they are both the same, but recent version of modutils use /etc/​modules.conf instead. Nothing to worry about as such, optionally please update to the latest version of modutils. This should solve your problem.

Here's the example for this card. Copy and paste this to the bottom of your /etc/​modules.conf file.

Note: 

Debian GNU/Linux users need to save this information into a file in the /etc/​modutils/ directory (eg. /etc/​modutils/​alsa) and run update-modules.

Note also that the kernel module soundcore has been renamed in Debian kernels >2.6.23 into snd. A workaround is to put a symlink at /lib/modules/x.x.xx/kernel/sound/soundcore.ko pointing to snd.ko


       # ALSA portion
       alias char-major-116 snd
       alias snd-card-0 snd-cs4281
       # module options should go here
       
       # OSS/Free portion
       alias char-major-14 soundcore
       alias sound-slot-0 snd-card-0
       
       # card #1
       alias sound-service-0-0 snd-mixer-oss
       alias sound-service-0-1 snd-seq-oss
       alias sound-service-0-3 snd-pcm-oss
       alias sound-service-0-8 snd-seq-oss
       alias sound-service-0-12 snd-pcm-oss

To copy and paste the above to your /etc/​modules.conf file follow these instructions.

modules.conf

This is a short explanation of what happens in the /etc/​modules.conf file.

Native devices

After the main multiplexer is loaded, its code automatically requests the top level sound card module. String snd-card-%i is requested for native devices where %i is the sound card number, counted from zero (the first sound card) to seven (the eighth sound card). String sound-slot-%i is requested for native devices where %i is slot number for the corresponding ALSA owner (which is basically the sound card number). The options line allows you to set various configuration options before the module is loaded. String id (or snd_id) lets you set the name of the card which is then returned in the /proc/​asound/​cards file, i.e. to user space applications. Other options may be available depending on the specific card. Options for these cards are found in the INSTALL file or above.

       username@hostname# pico /etc/modules.conf
       
       # ALSA portion
       alias snd-card-0 snd-hda-intel
       alias snd-card-1 snd-cmipci
       options snd-cmipci id="first" mpu_port=0x330
       
       # OSS/Free portion
       alias sound-slot-0 snd-card-0
       alias sound-slot-1 snd-card-1
NB: 

For drivers older than 0.9.0rc5 use:

       options snd-cmipci snd_id="first" snd_mpu_port=0x330


NB: 

The "snd_" prefix has been removed from the module options to fit with the kernel standard.


Autoloading OSS/free emulation

At this point we are finished with the configuration for ALSA native devices, but you may also need autoloading for the OSS/Free emulation modules, an ALSA add-on. At this time only one module does not depend on any others, thus must be loaded separately: snd-pcm1-oss. String sound-service-%i-%i is required for OSS/Free service where the first %i is the slot number/​sound card number and the second %i is the service number.

       username@hostname# pico /etc/modules.conf
       
       # OSS/Free portion - card #1
       alias sound-slot-0 snd-card-0
       alias sound-service-0-0 snd-mixer-oss
       alias sound-service-0-1 snd-seq-oss
       alias sound-service-0-3 snd-pcm-oss
       alias sound-service-0-8 snd-seq-oss
       alias sound-service-0-12 snd-pcm-oss
       
       # OSS/Free portion - card #2 (cmipci)
       alias sound-slot-1 snd-card-1
       alias sound-service-1-0 snd-mixer-oss
       alias sound-service-1-3 snd-pcm-oss
       alias sound-service-1-12 snd-pcm-oss

The alias for snd-seq-oss is not necessary on the second device, because there is only one /dev/​sequencer regardless how many devices you have.

The .asoundrc file

This file allows you to have more advanced control over your card/​device. For most setups the default, system-wide configuration is sufficient. You may change this file only for special setup. The .asoundrc file consists of definitions for the various sound devices available in your system. It also provides access to the pcm plugins in alsa-lib. These allow you to do tricky things like combine your cards into one or access multiple I/O streams on your multi-channel card.

Below is the most basic definition (only example - not required to define at all).

Make a file called .asoundrc in your home and/​or root directory:

       vi ~/.asoundrc

Copy and paste the following into the file, then save it:

       pcm.cs4281 {
          type hw
          card 0
       }
       
       ctl.cs4281 {
          type hw
          card 0
       }

Software volume control

If your card doesn't have hardware volume control (e. g. Asus Xonar XD/XDG), you might want to create software Master control. Edit .asoundrc as follows.

       pcm.softvol {
          type softvol
          slave {
             pcm "dmix"
          }
          control {
             name "Master"
             card 0
          }
       }
       
       pcm.!default {
         type plug
         slave.pcm "softvol"
       }

Restart alsa, then open a music player, play a file and close the player. Then check alsamixer, as you should have a Master volume control. Note that this control doesn't have a mute option.

Links

Generic

Specific

User information

Enabling Software Mixing for Cirrus Logic CS4281

(I'm not a Linux Guru so this guide is to be used at own risk. It worked for me. Tested on Ubuntu 7.04)

Since this card doesnot support Hardware Mixing under ALSA, you need to allow "Software Mixing". Software Mixing is the ability to play multiple sound files or applications at the same time through the same device.

dmix

These days we have a native plugin for ALSA called the dmix (direct mixing) plugin. It allows software mixing in an easy to use syntax and without the hassle of installing/understanding a new application first.

A very interesting and potentially extremely useful aspect of this plugin is using it combined with the default plugin name. In theory this means all applications that have native ALSA support will share the sound device. In practice not many applications are able to take advantage of this functionality yet. However if you have time to test and report your findings to the application developers it is worth a try:

But first you need to know a bit about the file where we will store dmix configuration.

The .asoundrc file

This file allows the you to have more advanced control over your card/device. The .asoundrc file consists of definitions of the various cards available in your system. It also gives you access to the pcm plugins in alsa-lib. These allow you to do tricky things like combine your cards into one or access multiple i/o's on your mulitchannel card.

Neither the .asoundrc nor the asound.conf files are required for ALSA to work properly. Most applications will work without them. They are used to allow extra functionality, such as routing and sample-rate conversion, through the alsa-lib layer.

Where does asoundrc live?

The asoundrc file is typically installed in a user's home directory

$HOME/.asoundrc

and is called from

/usr/share/alsa/alsa.conf

It is also possible to install a system wide configuration file as

/etc/asound.conf

When an alsa application starts both configuration files are read.

Enabling Software Mixing:

Make a file called .asoundrc in your home and/or root directory.

       vi /home/xxx/.asoundrc

copy and paste the following into the file then save it.

   pcm.!default {
	type plug
	slave.pcm "dmixer"
    }

 
    pcm.dmixer  {
	type dmix
	ipc_key 1024
	slave {
	    pcm "hw:0,0"
	    period_time 0
	    period_size 1024
	    buffer_size 4096
	    rate 44100
	}
	bindings {
	    0 0
	    1 1
	}
    }
 
    ctl.dmixer {
	type hw
	card 0
    }


Now try:

aplay -f cd -D default test.wav

on multiple consoles.

Some notes:

The dmix PCM name is already defined in the global configuration file /usr/share/alsa/alsa.conf.

- The default sample rate for this device is 48000Hz. If you would like to change it use:

	aplay -D"plug:'dmix:RATE=44100'" test.wav

- An example command for dmix plugin to use 44100Hz sample-rate and hw:1,0 output device:

	aplay -Dplug:\'dmix:SLAVE=\"hw:1,0\",RATE=44100\' test.wav

- The dmix PCM name is already defined in the global configuration file /usr/share/alsa/alsa.conf.

Defaults are:

SLAVE="hw:0,0",RATE=48000

NB the dmix plugin is not based on client/server architecture, but it writes directly to the soundcard's DMA buffer. There is no limit to the amount of instances that can be run at one time .

Saad Bin Javed

Jul 2, 2007

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