Problem with broken sound on some ThinkPads

Information about the phenomena of broken sound on 600/E/X type ThinkPads.

Problem description

First of all, be aware that even though the sound chip is a Crystal SoundFusion 4610, you'll have to use the cs4236 driver to enable sound on this machine, since this driver supports the CS4239 emulation that the 4610 chip offers.

Done that you might experience the phenomena that your sound goes into a loop after about a second just like a scratched record.

Affected Models

• ThinkPad 600, 600E, 600X
• ThinkPad 770Z

Affected Operating Systems

• Linux, all flavours

Status

Here's a reasonable explanation of what happens:

The problem with the 600 series is that there is not one, not two, but THREE chips that look like sound cards to Linux. The actual Crystal chip is one of them, the mwave is another, and the video chipset has a DSP that can be used as sound circuitry if a designer opted to do so.

Solutions

Compile the sound driver as module and load it after everything else. You can create a boot script with the following line for that:

/sbin/modprobe snd-cs4236 index=0 port=0x530 cport=0x538 irq=5 dma1=1 dma2=0 isapnp=0

This is reported to work at least with kernel 2.6.9.