man oss_ich (7): Intel ICH/SiS7012/Nvidia/AMD audio device driver.

DESCRIPTION

Open Sound System driver for Intel ICH, nVidia Nforce, AMD and SiS 7012 devices.

intelpci_rate_tuning=<NNN> (default is 240) Some Compaq Deskpro models (EN and EX at least) and certain Dell models play and record audio at a higher speed than what is expected. If you have an Intel815 motherboard with an AD1885 you can try setting the parameter to 240, 280 or 330 and see which works for your system. The way to figure out the the right intelpci_rate_tuning value is using the osstest application. It reports a sample rate drift value ("Sample rate drift" or "srate drift"). Use the following formula (round the result to the nearest integer):

<intelpci_rate_tuning = (240*(drift+100))/100>
intelpci_force_mmio=<0|1> (default is 0=Disable) This option can be used to force the ICH4/ICH5 and ICH6 controllers to run in memory mapped mode to free up I/O address space.
ich_jacksense=<0|1> (default is 0) Force use of jacksensing on some AD198x mixers.

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