What is it?
-----------

It unhides the SMBus of Intel ICH southbridges hidden on Asus P4B series
and some other Asus and non-Asus systems. It is implemented as a shell
script for kernel 2.6.5 and later: unhide_ICH_SMBus.

It works with the following chips:
 * ICH2   (82801BA)
 * ICH2-M (82801BAM)
 * ICH3   (82801CA)
 * ICH3-M (82801CAM)
 * ICH4   (82801DB)
 * ICH4-M (82801DBM)
 * ICH5   (82801EB)

ASUS switches off the SMBus PCI Device in the i801 ICH chip. I spoke twice
with the German support and learned that: "We do not want the users to be
irritated by just another PCI Device in the Win98 device manager."
Really funny :-).

Activation is normally handled by the code in drivers/pci/quirks.c in the
kernel source. If the quirks code does not activate your SMBus, you may:

 * first of all, read the paragraph "Hidden ICH SMBus" in
   Documentation/i2c/busses/i2c-i801 in the kernel source.

 * check if you have kernel version from 2.6.16 to 2.6.19
   If so, you need to disable ACPI sleep support and recompile kernel. 
   If you don't use suspend try below instead of recompilation.

 * run as root the ./unhide_ICH_SMBus script. It will unhide the bus 
   and load the i2c-i801 driver. Beware that you should then no longer
   use system suspend as bad things might happen on resume.

 * if above script works and you have latest kernel, you may 
   try to fix the quirks.c, recompile and test your new kernel,
   and then submit a patch to us. Contact us if you need assistance.