mirror of
https://github.com/lm-sensors/lm-sensors.git
synced 2026-11-09 16:21:51 +00:00
Frodo Looijaard
765c6e0c84
git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@356 7894878c-1315-0410-8ee3-d5d059ff63e0
36 lines
1.9 KiB
Plaintext
36 lines
1.9 KiB
Plaintext
The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of
|
|
functionality. Among other things, it implements the PCI bus. One of its
|
|
minor functions is implementing a System Management Bus. This is a true
|
|
SMBus - you can not access it on I2C levels. The good news is that it
|
|
natively understands SMBus commands and you do not have to worry about
|
|
timing problems. The bad news is that non-SMBus devices connected to it
|
|
can confuse it mightily. Yes, this is known to happen...
|
|
|
|
Cat /proc/pci, and see whether it contains an entry like this:
|
|
|
|
Bus 0, device 1, function 3:
|
|
Bridge: Intel 82371AB PIIX4 ACPI (rev 1).
|
|
Medium devsel. Fast back-to-back capable.
|
|
|
|
Bus and device numbers may differ, but the function number must be identical
|
|
(like many PCI devices, the PIIX4 incorporates a number of different
|
|
'functions', which can be considered as separate devices). If you find such
|
|
an entry, you have a PIIX4 SMBus controller.
|
|
|
|
On some computers (most notably, some Dells), the SMBus is disabled by
|
|
default. If you use the insmod parameter 'force=1', the kernel module
|
|
will try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not
|
|
set up a correct address for this module, you could get in big trouble
|
|
(read: crashes, data corruption, etc.). Try this only as a last resort
|
|
(try BIOS updates first, for example), and backup first! An even more
|
|
dangerous option is 'force_addr=<IOPORT>'. This will not only enable the
|
|
PIIX4 like 'force' foes, but it will also set a new base I/O port address.
|
|
The SMBus parts of the PIIX4 needs a range of 8 of these addresses to
|
|
function correctly. If these addresses are already reserved by some other
|
|
device, you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY
|
|
SURE ABOUT WHAT YOU ARE DOING!
|
|
|
|
The PIIX4E is just an new version of the PIIX4; it is supported as well. The
|
|
PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use this
|
|
driver on those mainboards.
|