Revision 101e5c7470eb7f77ae87f966b9155f0dbb5b4698 authored by Linus Torvalds on 27 December 2012, 18:46:47 UTC, committed by Linus Torvalds on 27 December 2012, 18:46:47 UTC
Pull hwmon fixes from Guenter Roeck: - Report i2c errors to userspace in lm73 driver - Fix problem with DIV_ROUND_CLOSEST and unsigned divisors in emc6w201 driver * tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging: hwmon: (emc6w201) Fix DIV_ROUND_CLOSEST problem with unsigned divisors hwmon: (lm73} Detect and report i2c bus errors
ten-bit-addresses
The I2C protocol knows about two kinds of device addresses: normal 7 bit
addresses, and an extended set of 10 bit addresses. The sets of addresses
do not intersect: the 7 bit address 0x10 is not the same as the 10 bit
address 0x10 (though a single device could respond to both of them).
I2C messages to and from 10-bit address devices have a different format.
See the I2C specification for the details.
The current 10 bit address support is minimal. It should work, however
you can expect some problems along the way:
* Not all bus drivers support 10-bit addresses. Some don't because the
hardware doesn't support them (SMBus doesn't require 10-bit address
support for example), some don't because nobody bothered adding the
code (or it's there but not working properly.) Software implementation
(i2c-algo-bit) is known to work.
* Some optional features do not support 10-bit addresses. This is the
case of automatic detection and instantiation of devices by their,
drivers, for example.
* Many user-space packages (for example i2c-tools) lack support for
10-bit addresses.
Note that 10-bit address devices are still pretty rare, so the limitations
listed above could stay for a long time, maybe even forever if nobody
needs them to be fixed.
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