linux.git/drivers/cpufreq/intel_pstate.c, branch v3.19

intel_pstate: Add a few comments

2014-12-10T23:24:42+00:00

Add a few comments in the code which calculates busyness to
clarify parts of the algorithm.

Signed-off-by: Kristen Carlson Accardi 
Signed-off-by: Rafael J. Wysocki

intel_pstate: add kernel parameter to force loading

2014-12-10T23:23:48+00:00

To force loading on Oracle Sun X86 servers, provide one kernel command line
parameter

  intel_pstate = force

For those who are aware of the risk of no power capping capabily working
and try to get better performance with this driver.

Signed-off-by: Ethan Zhao 
Tested-by: Alexey Kodanev 
Reviewed-by: Linda Knippers 
Acked-by: Kristen Carlson Accardi 
Signed-off-by: Rafael J. Wysocki

intel_pstate: skip this driver if Sun server has _PPC method

2014-12-03T01:56:04+00:00

Oracle Sun X86 servers have dynamic power capping capability that works via
ACPI _PPC method etc, so skip loading this driver if Sun server has ACPI _PPC
enabled.

Signed-off-by: Ethan Zhao 
Tested-by: Linda Knippers 
Acked-by: Kristen Carlson Accardi 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Add CPUID for BDW-H CPU

2014-11-11T23:04:38+00:00

Add BDW-H to the list of supported processors.

Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Add support for HWP

2014-11-11T23:04:38+00:00

Add support of Hardware Managed Performance States (HWP) described in Volume 3
section 14.4 of the SDM.

With HWP enbaled intel_pstate will no longer be responsible for selecting P
states for the processor. intel_pstate will continue to register to
the cpufreq core as the scaling driver for CPUs implementing
HWP. In HWP mode intel_pstate provides three functions reporting
frequency to the cpufreq core, support for the set_policy() interface
from the core and maintaining the intel_pstate sysfs interface in
/sys/devices/system/cpu/intel_pstate.  User preferences expressed via
the set_policy() interface or the sysfs interface are forwared to the
CPU via the HWP MSR interface.

Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Correct BYT VID values.

2014-10-23T21:00:00+00:00

Using a VID value that is not high enough for the requested P state can
cause machine checks. Add a ceiling function to ensure calulated VIDs
with fractional values are set to the next highest integer VID value.

The algorythm for calculating the non-trubo VID from the BIOS writers
guide is:
 vid_ratio = (vid_max - vid_min) / (max_pstate - min_pstate)
 vid = ceiling(vid_min + (req_pstate - min_pstate) * vid_ratio)

Cc: All applicable 
Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Fix BYT frequency reporting

2014-10-23T20:59:59+00:00

BYT has a different conversion from P state to frequency than the core
processors.  This causes the min/max and current frequency to be
misreported on some BYT SKUs. Tested on BYT N2820, Ivybridge and
Haswell processors.

Link: https://bugzilla.yoctoproject.org/show_bug.cgi?id=6663
Cc: All applicable 
Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Don't lose sysfs settings during cpu offline

2014-10-23T20:59:59+00:00

The user may have custom settings don't destroy them during suspend.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=80651
Reported-by: Tobias Jakobi 
Cc: All applicable 
Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

cpufreq: intel_pstate: Reflect current no_turbo state correctly

2014-10-23T20:59:59+00:00

Some BIOSes modify the state of MSR_IA32_MISC_ENABLE_TURBO_DISABLE
based on the current power source for the system battery AC vs
battery. Reflect the correct current state and ability to modify the
no_turbo sysfs file based on current state of
MSR_IA32_MISC_ENABLE_TURBO_DISABLE.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=83151
Cc: All applicable 
Signed-off-by: Gabriele Mazzotta 
Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

cpufreq: intel_pstate: Fix setting max_perf_pct in performance policy

2014-10-23T20:59:59+00:00

Code which changes policy to powersave changes also max_policy_pct based on
max_freq. Code which change max_perf_pct has upper limit base on value
max_policy_pct. When policy is changing from powersave back to performance
then max_policy_pct is not changed. Which means that changing max_perf_pct is
not possible to high values if max_freq was too low in powersave policy.

Test case:

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
800000
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
3300000
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
performance
$ cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
100

$ echo powersave > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
$ echo 800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
$ echo 20 > /sys/devices/system/cpu/intel_pstate/max_perf_pct

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
powersave
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
800000
$ cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
20

$ echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
$ echo 3300000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
$ echo 100 > /sys/devices/system/cpu/intel_pstate/max_perf_pct

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
performance
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
3300000
$ cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
24

And now intel_pstate driver allows to set maximal value for max_perf_pct based
on max_policy_pct which is 24 for previous powersave max_freq 800000.

This patch will set default value for max_policy_pct when setting policy to
performance so it will allow to set also max value for max_perf_pct.

Signed-off-by: Pali Rohár 
Cc: All applicable 
Acked-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki