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Date: Wed, 26 Jan 2022 15:34:49 -0800 From: Stephane Eranian <eranian@...gle.com> To: linux-kernel@...r.kernel.org Cc: peterz@...radead.org, kim.phillips@....com, acme@...hat.com, jolsa@...hat.com, songliubraving@...com Subject: [PATCH v5 08/13] ACPI: add perf low power callback This patch add an optional callback needed by some PMU features, e.g., AMD BRS, to give a chance to the perf_events code to change its state before going to low power and after coming back. The callback is void when the PERF_NEEDS_LOPWR_CB flag is not set. This flag must be set in arch specific perf_event.h header whenever needed. When not set, there is no impact of the ACPI code. Signed-off-by: Stephane Eranian <eranian@...gle.com> --- drivers/acpi/acpi_pad.c | 6 ++++++ drivers/acpi/processor_idle.c | 5 +++++ include/linux/perf_event.h | 6 ++++++ 3 files changed, 17 insertions(+) diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c index f45979aa2d64..a306a07a60b5 100644 --- a/drivers/acpi/acpi_pad.c +++ b/drivers/acpi/acpi_pad.c @@ -164,6 +164,9 @@ static int power_saving_thread(void *data) tsc_marked_unstable = 1; } local_irq_disable(); + + perf_lopwr_cb(true); + tick_broadcast_enable(); tick_broadcast_enter(); stop_critical_timings(); @@ -172,6 +175,9 @@ static int power_saving_thread(void *data) start_critical_timings(); tick_broadcast_exit(); + + perf_lopwr_cb(false); + local_irq_enable(); if (time_before(expire_time, jiffies)) { diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 86560a28751b..880c0a43a529 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -21,6 +21,7 @@ #include <linux/cpuidle.h> #include <linux/cpu.h> #include <linux/minmax.h> +#include <linux/perf_event.h> #include <acpi/processor.h> /* @@ -544,6 +545,8 @@ static void wait_for_freeze(void) */ static void __cpuidle acpi_idle_do_entry(struct acpi_processor_cx *cx) { + perf_lopwr_cb(true); + if (cx->entry_method == ACPI_CSTATE_FFH) { /* Call into architectural FFH based C-state */ acpi_processor_ffh_cstate_enter(cx); @@ -554,6 +557,8 @@ static void __cpuidle acpi_idle_do_entry(struct acpi_processor_cx *cx) inb(cx->address); wait_for_freeze(); } + + perf_lopwr_cb(false); } /** diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 496eb6aa6e54..1b98e46588bc 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1676,4 +1676,10 @@ typedef int (perf_snapshot_branch_stack_t)(struct perf_branch_entry *entries, unsigned int cnt); DECLARE_STATIC_CALL(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t); +#ifndef PERF_NEEDS_LOPWR_CB +static inline void perf_lopwr_cb(bool mode) +{ +} +#endif + #endif /* _LINUX_PERF_EVENT_H */ -- 2.35.0.rc0.227.g00780c9af4-goog
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