Somewhat useful debugging messages are available. The choice of
messages is controlled by a bitmap. This may be specified as a
module argument (kernel command line argument as well?), changed
dynamically using an ioctl (Get the debug utility, iadbg, from
<ftp://ftp.iphase.com/pub/atm/pci/>).

See the file <file:drivers/atm/iphase.h> for the meanings of the
bits in the mask.

When active, these messages can have a significant impact on the
speed of the driver, and the size of your syslog files! When
inactive, they will have only a modest impact on performance.