kernel/linux.git/drivers/cpufreq/cppc_cpufreq.c, branch v6.19.11

cpufreq: CPPC: Don't warn if FIE init fails to read counters

2025-10-28T05:10:47+00:00

During the CPPC FIE initialization, reading perf counters on offline cpus should be expected to fail. Don't warn on this case. Also, change the error log level to debug since FIE is optional. Co-developed-by: Bowen Yu Signed-off-by: Bowen Yu # Changing loglevel to debug Signed-off-by: Jie Zhan [ Viresh: Added back the dropped comment. ] Signed-off-by: Viresh Kumar

ACPI: CPPC: Do not use CPUFREQ_ETERNAL as an error value

2025-10-01T11:57:13+00:00

Instead of using CPUFREQ_ETERNAL for signaling an error condition in cppc_get_transition_latency(), change the return value type of that function to int and make it return a proper negative error code on failures. No intentional functional impact. Reviewed-by: Mario Limonciello (AMD) Reviewed-by: Jie Zhan Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar Reviewed-by: Qais Yousef

cpufreq: CPPC: Avoid using CPUFREQ_ETERNAL as transition delay

2025-10-01T11:56:57+00:00

If cppc_get_transition_latency() returns CPUFREQ_ETERNAL to indicate a failure to retrieve the transition latency value from the platform firmware, the CPPC cpufreq driver will use that value (converted to microseconds) as the policy transition delay, but it is way too large for any practical use. Address this by making the driver use the cpufreq's default transition latency value (in microseconds) as the transition delay if CPUFREQ_ETERNAL is returned by cppc_get_transition_latency(). Fixes: d4f3388afd48 ("cpufreq / CPPC: Set platform specific transition_delay_us") Cc: 5.19+ # 5.19 Signed-off-by: Rafael J. Wysocki Reviewed-by: Mario Limonciello (AMD) Reviewed-by: Jie Zhan Acked-by: Viresh Kumar Reviewed-by: Qais Yousef

cpufreq: CPPC: Use scope-based cleanup helper

2025-08-29T06:03:57+00:00

Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy) annotation for policy references. This reduces the risk of reference counting mistakes and aligns the code with the latest kernel style. No functional change intended. Signed-off-by: Zihuan Zhang [ Viresh: Minor changes ] Signed-off-by: Viresh Kumar

cpufreq: Remove unused parameter in cppc_perf_from_fbctrs()

2025-08-11T06:54:51+00:00

Remove the unused parameter cppc_cpudata* cpu_data in cppc_perf_from_fbctrs(). Signed-off-by: BowenYu Signed-off-by: Viresh Kumar

cpufreq: CPPC: Mark driver with NEED_UPDATE_LIMITS flag

2025-07-22T10:13:12+00:00

AMU counters on certain CPPC-based platforms tend to yield inaccurate delivered performance measurements on systems that are idle/mostly idle. This results in an inaccurate frequency being stored by cpufreq in its policy structure when the CPU is brought online. [1] Consequently, if the userspace governor tries to set the frequency to a new value, there is a possibility that it would be the erroneous value stored earlier. In such a scenario, cpufreq would assume that the requested frequency has already been set and return early, resulting in the correct/new frequency request never making it to the hardware. Since the operating frequency is liable to this sort of inconsistency, mark the CPPC driver with CPUFREQ_NEED_UPDATE_LIMITS so that it is always invoked when a target frequency update is requested. Link: https://lore.kernel.org/linux-pm/20250619000925.415528-3-pmalani@google.com/ [1] Suggested-by: Rafael J. Wysocki Signed-off-by: Prashant Malani Acked-by: Viresh Kumar Link: https://patch.msgid.link/20250722055611.130574-2-pmalani@google.com Signed-off-by: Rafael J. Wysocki

cpufreq: CPPC: Remove forward declaration of cppc_cpufreq_register_em()

2025-06-18T19:03:52+00:00

cppc_cpufreq_register_em() is only used in populate_efficiency_class(). A forward declaration of it is not necessary. Move cppc_cpufreq_register_em() in front of populate_efficiency_class() and remove the forward declaration of cppc_cpufreq_register_em(). No functional change. Signed-off-by: Lifeng Zheng Link: https://patch.msgid.link/20250526113057.3086513-4-zhenglifeng1@huawei.com [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki

cpufreq: CPPC: Do not return a value from populate_efficiency_class()

2025-06-18T19:03:52+00:00

The return value of populate_efficiency_class() is never needed and the result of it doesn't affect the initialization of cppc_cpufreq. It makes more sense to change it into a void function. Signed-off-by: Lifeng Zheng Link: https://patch.msgid.link/20250526113057.3086513-3-zhenglifeng1@huawei.com [ rjw: Subject and changelog edits ] Signed-off-by: Rafael J. Wysocki

cpufreq: CPPC: Remove cpu_data_list

2025-06-18T19:03:52+00:00

After commit a28b2bfc099c ("cppc_cpufreq: replace per-cpu data array with a list"), cpu_data can be got from policy->driver_data, so cpu_data_list is not actually needed and can be removed. Signed-off-by: Lifeng Zheng Link: https://patch.msgid.link/20250526113057.3086513-2-zhenglifeng1@huawei.com Signed-off-by: Rafael J. Wysocki

cpufreq: CPPC: Add support for autonomous selection

2025-05-21T20:47:44+00:00

Add sysfs interfaces for CPPC autonomous selection in the cppc_cpufreq driver. Signed-off-by: Lifeng Zheng Reviewed-by: Sumit Gupta Acked-by: Viresh Kumar Link: https://patch.msgid.link/20250507031941.2812701-1-zhenglifeng1@huawei.com [ rjw: Subject edits ] Signed-off-by: Rafael J. Wysocki