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linux-stable/drivers/cpufreq
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Pierre Gondois d76c0f10bc cpufreq: CPPC: Fix performance/frequency conversion 
[ Upstream commit ec1c7ad476 ]

CPUfreq governors request CPU frequencies using information
on current CPU usage. The CPPC driver converts them to
performance requests. Frequency targets are computed as:
	target_freq = (util / cpu_capacity) * max_freq
target_freq is then clamped between [policy->min, policy->max].

The CPPC driver converts performance values to frequencies
(and vice-versa) using cppc_cpufreq_perf_to_khz() and
cppc_cpufreq_khz_to_perf(). These functions both use two different
factors depending on the range of the input value. For
cppc_cpufreq_khz_to_perf():
- (NOMINAL_PERF / NOMINAL_FREQ) or
- (LOWEST_PERF / LOWEST_FREQ)
and for cppc_cpufreq_perf_to_khz():
- (NOMINAL_FREQ / NOMINAL_PERF) or
- ((NOMINAL_PERF - LOWEST_FREQ) / (NOMINAL_PERF - LOWEST_PERF))

This means:
1- the functions are not inverse for some values:
   (perf_to_khz(khz_to_perf(x)) != x)
2- cppc_cpufreq_perf_to_khz(LOWEST_PERF) can sometimes give
   a different value from LOWEST_FREQ due to integer approximation
3- it is implied that performance and frequency are proportional
   (NOMINAL_FREQ / NOMINAL_PERF) == (LOWEST_PERF / LOWEST_FREQ)

This patch changes the conversion functions to an affine function.
This fixes the 3 points above.

Suggested-by: Lukasz Luba <lukasz.luba@arm.com>
Suggested-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2022-04-13 19:27:24 +02:00
..
Kconfig cpufreq: Kconfig: fix documentation links 2021-04-21 19:00:42 +02:00
Kconfig.arm cpufreq: mediatek-hw: Add support for CPUFREQ HW 2021-09-06 15:15:19 +05:30
Kconfig.powerpc
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Kconfig.x86 cpufreq: amd-pstate: Fix Kconfig dependencies for AMD P-State 2022-01-06 18:31:33 +01:00
Makefile cpufreq: amd-pstate: Add trace for AMD P-State module 2021-12-30 18:51:39 +01:00
acpi-cpufreq.c cpufreq: Introducing CPUFREQ_RELATION_E 2021-10-05 16:33:05 +02:00
amd-pstate-trace.c cpufreq: amd-pstate: Add trace for AMD P-State module 2021-12-30 18:51:39 +01:00
amd-pstate-trace.h cpufreq: amd-pstate: Add trace for AMD P-State module 2021-12-30 18:51:39 +01:00
amd-pstate.c cpufreq: amd-pstate: Fix struct amd_cpudata kernel-doc comment 2022-01-06 18:28:26 +01:00
amd_freq_sensitivity.c cpufreq: Introducing CPUFREQ_RELATION_E 2021-10-05 16:33:05 +02:00
armada-8k-cpufreq.c cpufreq: ap806: Add missing MODULE_DEVICE_TABLE 2020-12-07 13:02:37 +05:30
armada-37xx-cpufreq.c cpufreq: armada-37xx: forbid cpufreq for 1.2 GHz variant 2021-08-09 09:31:22 +05:30
bmips-cpufreq.c
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brcmstb-avs-cpufreq.c cpufreq: brcmstb-avs-cpufreq: Fix resource leaks in ->remove() 2021-01-18 12:23:43 +05:30
cppc_cpufreq.c cpufreq: CPPC: Fix performance/frequency conversion 2022-04-13 19:27:24 +02:00
cpufreq-dt-platdev.c cpufreq: blocklist more Qualcomm platforms in cpufreq-dt-platdev 2021-08-30 10:43:35 +05:30
cpufreq-dt.c cpufreq: dt: Use .register_em() to register with energy model 2021-08-12 09:54:07 +05:30
cpufreq-dt.h cpufreq: dt: Allow platform specific intermediate callbacks 2020-03-12 15:43:52 +05:30
cpufreq-nforce2.c cpufreq: Avoid creating excessively large stack frames 2020-01-27 10:33:33 +01:00
cpufreq.c cpufreq: Reintroduce ready() callback 2022-02-09 13:18:49 +05:30
cpufreq_conservative.c cpufreq: use default_groups in kobj_type 2021-12-28 19:13:12 +01:00
cpufreq_governor.c cpufreq: cpufreq_governor: Demote store_sampling_rate() header to standard comment block 2020-07-15 15:17:06 +02:00
cpufreq_governor.h cpufreq: Introduce governor flags 2020-11-10 18:31:17 +01:00
cpufreq_governor_attr_set.c cpufreq: schedutil: Destroy mutex before kobject_put() frees the memory 2021-09-14 19:01:36 +02:00
cpufreq_ondemand.c cpufreq: use default_groups in kobj_type 2021-12-28 19:13:12 +01:00
cpufreq_ondemand.h
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cpufreq_performance.c cpufreq: Introduce CPUFREQ_GOV_STRICT_TARGET 2020-11-10 18:31:17 +01:00
cpufreq_powersave.c cpufreq: Introduce CPUFREQ_GOV_STRICT_TARGET 2020-11-10 18:31:17 +01:00
cpufreq_stats.c cpufreq: stats: Clean up local variable in cpufreq_stats_create_table() 2021-06-07 13:47:57 +02:00
cpufreq_userspace.c cpufreq: Register governors at core_initcall 2020-07-02 13:03:30 +02:00
davinci-cpufreq.c cpufreq: Remove CPUFREQ_STICKY flag 2021-02-04 19:23:20 +01:00
e_powersaver.c cpufreq: e_powersaver: remove unreachable break 2020-10-27 18:42:54 +01:00
elanfreq.c cpufreq: Convert to new X86 CPU match macros 2020-03-24 21:31:27 +01:00
freq_table.c cpufreq: Fix scaling_{available,boost}_frequencies_show() comments 2021-03-26 17:43:48 +01:00
gx-suspmod.c cpufreq: Avoid creating excessively large stack frames 2020-01-27 10:33:33 +01:00
highbank-cpufreq.c cpufreq: highbank: Add missing MODULE_DEVICE_TABLE 2020-12-07 13:02:37 +05:30
ia64-acpi-cpufreq.c ia64: fix format string for ia64-acpi-cpu-freq 2021-03-19 17:26:20 +01:00
imx-cpufreq-dt.c cpufreq: imx-cpufreq-dt: support i.MX7ULP 2020-04-28 14:26:20 +05:30
imx6q-cpufreq.c cpufreq: imx6q: Use .register_em() to register with energy model 2021-08-12 09:54:07 +05:30
intel_pstate.c cpufreq: intel_pstate: Update cpuinfo.max_freq on HWP_CAP changes 2021-12-22 18:36:07 +01:00
kirkwood-cpufreq.c
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longhaul.c cpufreq: Fix fall-through warning for Clang 2021-07-13 11:53:07 -05:00
longhaul.h
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longrun.c cpufreq: Convert to new X86 CPU match macros 2020-03-24 21:31:27 +01:00
loongson1-cpufreq.c cpufreq: Remove CPUFREQ_STICKY flag 2021-02-04 19:23:20 +01:00
loongson2_cpufreq.c cpufreq: loongson2: Remove unused linux/sched.h headers 2021-06-07 17:43:52 +02:00
maple-cpufreq.c
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mediatek-cpufreq-hw.c cpufreq: mediatek-hw: Fix double devm_remap in hotplug case 2021-12-27 09:44:53 +05:30
mediatek-cpufreq.c cpufreq: mediatek: Use .register_em() to register with energy model 2021-08-12 09:54:07 +05:30
mvebu-cpufreq.c
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omap-cpufreq.c cpufreq: omap: Use .register_em() to register with energy model 2021-08-12 09:54:07 +05:30
p4-clockmod.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
pasemi-cpufreq.c cpufreq: pasemi: Include header file for {check,restore}_astate prototypes 2020-07-15 15:17:06 +02:00
pcc-cpufreq.c cpufreq: pcc-cpufreq: Mark sometimes used ID structs as __maybe_unused 2020-07-15 15:17:06 +02:00
pmac32-cpufreq.c cpufreq: Remove unused flag CPUFREQ_PM_NO_WARN 2021-02-04 19:25:47 +01:00
pmac64-cpufreq.c
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powernow-k6.c cpufreq: Convert to new X86 CPU match macros 2020-03-24 21:31:27 +01:00
powernow-k7.c cpufreq: Convert to new X86 CPU match macros 2020-03-24 21:31:27 +01:00
powernow-k7.h
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powernow-k8.c cpufreq: Replace deprecated CPU-hotplug functions 2021-08-04 20:16:32 +02:00
powernow-k8.h
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powernv-cpufreq.c cpufreq: Introducing CPUFREQ_RELATION_E 2021-10-05 16:33:05 +02:00
ppc_cbe_cpufreq.c
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ppc_cbe_cpufreq.h
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ppc_cbe_cpufreq_pervasive.c
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ppc_cbe_cpufreq_pmi.c
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pxa2xx-cpufreq.c
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pxa3xx-cpufreq.c
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qcom-cpufreq-hw.c cpufreq: qcom-hw: Delay enabling throttle_irq 2022-02-09 13:18:49 +05:30
qcom-cpufreq-nvmem.c cpufreq: qcom-cpufreq-nvmem: fix reading of PVS Valid fuse 2022-04-08 13:58:24 +02:00
qoriq-cpufreq.c cpufreq: qoriq: convert to a platform driver 2020-05-07 10:47:27 +05:30
raspberrypi-cpufreq.c
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s3c24xx-cpufreq-debugfs.c ARM: s3c: remove cpufreq header dependencies 2020-08-20 17:52:05 +02:00
s3c24xx-cpufreq.c cpufreq: Remove CPUFREQ_STICKY flag 2021-02-04 19:23:20 +01:00
s3c64xx-cpufreq.c
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s3c2410-cpufreq.c cpufreq: s3c24xx: move low-level clk reg access into platform code 2020-08-20 17:53:22 +02:00
s3c2412-cpufreq.c cpufreq: s3c24xx: move low-level clk reg access into platform code 2020-08-20 17:53:22 +02:00
s3c2416-cpufreq.c
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s3c2440-cpufreq.c cpufreq: s3c244x: add fallthrough comments for switch 2021-10-04 11:43:14 +05:30
s5pv210-cpufreq.c cpufreq: Introducing CPUFREQ_RELATION_E 2021-10-05 16:33:05 +02:00
sa1100-cpufreq.c cpufreq: Remove CPUFREQ_STICKY flag 2021-02-04 19:23:20 +01:00
sa1110-cpufreq.c cpufreq: Remove CPUFREQ_STICKY flag 2021-02-04 19:23:20 +01:00
sc520_freq.c cpufreq: sc520_freq: add 'fallthrough' to one case 2021-05-21 18:52:13 +02:00
scmi-cpufreq.c cpufreq: scmi: Use .register_em() to register with energy model 2021-08-30 10:43:00 +05:30
scpi-cpufreq.c cpufreq: scpi: Use .register_em() to register with energy model 2021-08-30 10:42:45 +05:30
sh-cpufreq.c cpufreq: sh: Remove sh_cpufreq_cpu_ready() 2021-09-02 18:04:17 +02:00
sparc-us2e-cpufreq.c
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sparc-us3-cpufreq.c
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spear-cpufreq.c cpufreq: Remove CPUFREQ_STICKY flag 2021-02-04 19:23:20 +01:00
speedstep-centrino.c cpufreq: Convert to new X86 CPU match macros 2020-03-24 21:31:27 +01:00
speedstep-ich.c cpufreq: Convert to new X86 CPU match macros 2020-03-24 21:31:27 +01:00
speedstep-lib.c cpufreq: speedstep: remove unneeded semicolon 2020-10-28 18:04:07 +01:00
speedstep-lib.h
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speedstep-smi.c cpufreq: Convert to new X86 CPU match macros 2020-03-24 21:31:27 +01:00
sti-cpufreq.c cpufreq: st: Add missing MODULE_DEVICE_TABLE 2020-12-07 13:02:37 +05:30
sun50i-cpufreq-nvmem.c cpufreq: sun50i: Add missing MODULE_DEVICE_TABLE 2020-12-07 13:02:37 +05:30
tegra20-cpufreq.c cpufreq: tegra20: Use resource-managed API 2021-01-18 12:02:53 +05:30
tegra124-cpufreq.c
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tegra186-cpufreq.c cpufreq: tegra186/tegra194: Handle errors in BPMP response 2021-10-04 12:31:36 +05:30
tegra194-cpufreq.c cpufreq: tegra186/tegra194: Handle errors in BPMP response 2021-10-04 12:31:36 +05:30
ti-cpufreq.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
vexpress-spc-cpufreq.c cpufreq: vexpress: Drop unused variable 2021-10-04 11:25:21 +05:30