The cpufreq documentation specifies
policy->cpuinfo.transition_latency the time it takes on this CPU to
switch between two frequencies in
nanoseconds (if appropriate, else
specify CPUFREQ_ETERNAL)
currently pcc-cpufreq does not expose the value and sets it to zero. I
changed the pcc-cpufreq driver and it's documentation to conform to the
default value specified in Documentation/cpu-freq/cpu-drivers.txt
Signed-off-by: Jacob Tanenbaum <jtanenba@redhat.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Processor Clocking Control (PCC) is an interface between the BIOS and OSPM.
Based on the server workload, OSPM can request what frequency it expects
from a logical CPU, and the BIOS will achieve that frequency transparently.
This patch introduces driver support for PCC. OSPM uses the PCC driver to
communicate with the BIOS via the PCC interface.
There is a Documentation file that provides a link to the PCC
Specification, and also provides a summary of the PCC interface.
Currently, certain HP ProLiant platforms implement the PCC interface. However,
any platform whose BIOS implements the PCC Specification, can utilize this
driver.
V2 --> V1 changes (based on Dominik's suggestions):
- Removed the dependency on CPU_FREQ_TABLE
- "cpufreq_stats" will no longer PANIC. Actually, it will not load anymore
because it is not applicable.
- Removed the sanity check for target frequency in the ->target routine.
NOTE: A patch to sanitize the target frequency requested by "ondemand" is
needed to ensure that the target freq < policy->min.
Can this driver be queued up for the 2.6.33 tree?
Signed-off-by: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>
