the following patch was just integrated into master: commit 8b58555a396576d2ab85e0e724ca8cfd679bddfd Author: Duncan Laurie dlaurie@chromium.org Date: Mon Jul 16 12:27:42 2012 -0700
ACPI: Add support for runtime config TDP down
The required power MSRs are mirrored in MCHBAR so it is possible to configure TDP at runtime via ASL.
This adds the required fields and a set of methods to configure "TDP down" and "TDP nominal". It explicitly does not support "TDP up" at the moment.
PSSS: method is added to assist in searching the _PSS table for the appropriate entry that corresponds to the desired max non-turbo ratio.
STND: Set TDP Down from Nominal. This will limit CPU to the TDP down configuration by sequencing the required changes in the right order.
STDN: Set TDP Nominal from Down. This will set the CPU back to nominal configuration by sequencing the required changes in the correct (reverse) order.
This does not introduce any functional changes and must be paired with additional changes to be useful.
The current configured TDP can be checked to see that the transition to/from a desired level is successful.
> mmio_read8 0xfed15f50 0x00 # TDP-Nominal
> mmio_read8 0xfed15f50 0x01 # TDP-Down
Change-Id: I31a2f30cc9d134cc5eee980ae9288ae45e71c6e6 Signed-off-by: Duncan Laurie dlaurie@chromium.org
Build-Tested: build bot (Jenkins) at Wed Jul 25 04:23:22 2012, giving +1 Reviewed-By: Ronald G. Minnich rminnich@gmail.com at Thu Jul 26 20:33:05 2012, giving +2 See http://review.coreboot.org/1344 for details.
-gerrit