cpufreq: Introduce new relation for freq selection

Introduce CPUFREQ_RELATION_C for frequency selection.
It selects the frequency with the minimum euclidean distance to target.
In case of equal distance between 2 frequencies, it will select the
greater frequency.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: ondemand: Eliminate the deadband effect

Currently, ondemand calculates the target frequency proportional to load
using the formula:
	Target frequency = C * load
	where C = policy->cpuinfo.max_freq / 100

Though, in many cases, the minimum available frequency is pretty high and
the above calculation introduces a dead band from load 0 to
100 * policy->cpuinfo.min_freq / policy->cpuinfo.max_freq where the target
frequency is always calculated to less than policy->cpuinfo.min_freq and
the minimum frequency is selected.

For example: on Intel i7-3770 @ 3.4GHz the policy->cpuinfo.min_freq = 1600000
and the policy->cpuinfo.max_freq = 3400000 (without turbo). Thus, the CPU
starts to scale up at a load above 47.
On quad core 1500MHz Krait the policy->cpuinfo.min_freq = 384000
and the policy->cpuinfo.max_freq = 1512000. Thus, the CPU starts to scale
at load above 25.

Change the calculation of target frequency to eliminate the above effect using
the formula:

	Target frequency = A + B * load
	where A = policy->cpuinfo.min_freq and
	      B = (policy->cpuinfo.max_freq - policy->cpuinfo->min_freq) / 100

This will map load values 0 to 100 linearly to cpuinfo.min_freq to
cpuinfo.max_freq.

Also, use the CPUFREQ_RELATION_C in __cpufreq_driver_target to select the
closest frequency in frequency_table. This is necessary to avoid selection
of minimum frequency only when load equals to 0. It will also help for selection
of frequencies using a more 'fair' criterion.

Tables below show the difference in selected frequency for specific values
of load without and with this patch. On Intel i7-3770 @ 3.40GHz:
	Without			With
Load	Target	Selected	Target	Selected
0	0	1600000		1600000	1600000
5	170050	1600000		1690050	1700000
10	340100	1600000		1780100	1700000
15	510150	1600000		1870150	1900000
20	680200	1600000		1960200	2000000
25	850250	1600000		2050250	2100000
30	1020300	1600000		2140300	2100000
35	1190350	1600000		2230350	2200000
40	1360400	1600000		2320400	2400000
45	1530450	1600000		2410450	2400000
50	1700500	1900000		2500500	2500000
55	1870550	1900000		2590550	2600000
60	2040600	2100000		2680600	2600000
65	2210650	2400000		2770650	2800000
70	2380700	2400000		2860700	2800000
75	2550750	2600000		2950750	3000000
80	2720800	2800000		3040800	3000000
85	2890850	2900000		3130850	3100000
90	3060900	3100000		3220900	3300000
95	3230950	3300000		3310950	3300000
100	3401000	3401000		3401000	3401000

On ARM quad core 1500MHz Krait:
	Without			With
Load	Target	Selected	Target	Selected
0	0	384000		384000	384000
5	75600	384000		440400	486000
10	151200	384000		496800	486000
15	226800	384000		553200	594000
20	302400	384000		609600	594000
25	378000	384000		666000	702000
30	453600	486000		722400	702000
35	529200	594000		778800	810000
40	604800	702000		835200	810000
45	680400	702000		891600	918000
50	756000	810000		948000	918000
55	831600	918000		1004400	1026000
60	907200	918000		1060800	1026000
65	982800	1026000		1117200	1134000
70	1058400	1134000		1173600	1134000
75	1134000	1134000		1230000	1242000
80	1209600	1242000		1286400	1242000
85	1285200	1350000		1342800	1350000
90	1360800	1458000		1399200	1350000
95	1436400	1458000		1455600	1458000
100	1512000	1512000		1512000	1512000

Tested on Intel i7-3770 CPU @ 3.40GHz and on ARM quad core 1500MHz Krait
(Android smartphone).
Benchmarks on Intel i7 shows a performance improvement on low and medium
work loads with lower power consumption. Specifics:

Phoronix Linux Kernel Compilation 3.1:
Time: -0.40%, energy: -0.07%
Phoronix Apache:
Time: -4.98%, energy: -2.35%
Phoronix FFMPEG:
Time: -6.29%, energy: -4.02%

Also, running mp3 decoding (very low load) shows no differences with and
without this patch.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
powernow-k6: support 350MHz CPU

There exists 350MHz K6-2E+ CPU, so add it to the usual frequency table.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
MAINTAINERS: power_supply: update maintainership

Take over maintanence for orphaned power supply subsystem
and assign linux-pm@vger.kernel.org as mailing list.

Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'pm-general' into bleeding-edge

* pm-general:
  MAINTAINERS: power_supply: update maintainership
cpufreq: don't restore policy->cpus on failure to move kobj

While hot-unplugging policy->cpu, we call cpufreq_nominate_new_policy_cpu() to
nominate next owner of policy, i.e. policy->cpu. If we fail to move policy
kobject under the new policy->cpu, we try to update policy->cpus with the old
policy->cpu.

This would have been required in case old-CPU is removed from policy->cpus in
the first place. But its not done before calling
cpufreq_nominate_new_policy_cpu(), but during the POST_DEAD notification which
happens quite late in the hot-unplugging path.

So, this is just some useless code hanging around, get rid of it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: propagate error returned by kobject_move()

We are returning -EINVAL instead of the error returned from kobject_move() when
it fails. Propagate the actual error number.

Also add a meaningful print when sysfs_create_link() fails.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: move policy kobj to update_policy_cpu()

We are calling kobject_move() from two separate places currently and both these
places share another routine update_policy_cpu() which is handling everything
around updating policy->cpu. Moving ownership of policy->kobj also lies under
the role of update_policy_cpu() routine and must be handled from there.

So, Lets move kobject_move() to update_policy_cpu() and get rid of
cpufreq_nominate_new_policy_cpu() as it doesn't have anything significant left.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'pm-cpufreq-next' into bleeding-edge

* pm-cpufreq-next:
  cpufreq: move policy kobj to update_policy_cpu()
  cpufreq: propagate error returned by kobject_move()
  cpufreq: don't restore policy->cpus on failure to move kobj
  powernow-k6: support 350MHz CPU
  cpufreq: ondemand: Eliminate the deadband effect
  cpufreq: Introduce new relation for freq selection