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Revision 2ee27796f298b710992a677a7e4d35c8c588b17e authored by Hans de Goede on 30 December 2018, 17:27:15 UTC, committed by Ingo Molnar on 19 April 2019, 17:23:13 UTC 
x86/cpu/intel: Lower the "ENERGY_PERF_BIAS: Set to normal" message's log priority
 
The "ENERGY_PERF_BIAS: Set to 'normal', was 'performance'" message triggers
on pretty much every Intel machine. The purpose of log messages with
a warning level is to notify the user of something which potentially is
a problem, or at least somewhat unexpected.

This message clearly does not match those criteria, so lower its log
priority from warning to info.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181230172715.17469-1-hdegoede@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent 1de7edb
Raw File
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).
To avoid ambiguity, the user sees 10 bit addresses mapped to a different
address space, namely 0xa000-0xa3ff. The leading 0xa (= 10) represents the
10 bit mode. This is used for creating device names in sysfs. It is also
needed when instantiating 10 bit devices via the new_device file in sysfs.

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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