61 lines
2.1 KiB
Diff
61 lines
2.1 KiB
Diff
From ef42dfab80cff26850695de8c95c3e1ba294e05c Mon Sep 17 00:00:00 2001
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From: Alex Shi <alex.shi@linaro.org>
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Date: Thu, 12 Jan 2017 21:27:03 +0800
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Subject: [PATCH] CPU / PM: expose pm_qos_resume_latency for CPUs
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[ commit 37efa4b41ffb31dcdfc3beb97d47992bb2a083e5 from linux-stable ]
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The cpu-dma PM QoS constraint impacts all the cpus in the system. There is no way
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to let the user to choose a PM QoS constraint per cpu.
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The following patch exposes to the userspace a per cpu based sysfs file
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in order to let the userspace to change the value of the PM QoS latency
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constraint.
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This change is inoperative in its form and the cpuidle governors have to
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take into account the per cpu latency constraint in addition to the
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global cpu-dma latency constraint in order to operate properly.
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BTW
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The pm_qos_resume_latency usage defined in
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Documentation/ABI/testing/sysfs-devices-power
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The /sys/devices/.../power/pm_qos_resume_latency_us attribute
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contains the PM QoS resume latency limit for the given device,
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which is the maximum allowed time it can take to resume the
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device, after it has been suspended at run time, from a resume
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request to the moment the device will be ready to process I/O,
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in microseconds. If it is equal to 0, however, this means that
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the PM QoS resume latency may be arbitrary.
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Signed-off-by: Alex Shi <alex.shi@linaro.org>
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Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Signed-off-by: Alex Kozyrev <alex.kozyrev@windriver.com>
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Signed-off-by: Jim Somerville <Jim.Somerville@windriver.com>
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---
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drivers/base/cpu.c | 2 ++
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1 file changed, 2 insertions(+)
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diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
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index 65e786d..91d620f 100644
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--- a/drivers/base/cpu.c
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+++ b/drivers/base/cpu.c
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@@ -16,6 +16,7 @@
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#include <linux/acpi.h>
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#include <linux/tick.h>
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#include <linux/nospec.h>
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+#include <linux/pm_qos.h>
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#include "base.h"
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@@ -319,6 +320,7 @@ int register_cpu(struct cpu *cpu, int num)
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per_cpu(cpu_sys_devices, num) = &cpu->dev;
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if (!error)
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register_cpu_under_node(num, cpu_to_node(num));
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+ dev_pm_qos_expose_latency_limit(&cpu->dev, 0);
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#ifdef CONFIG_KEXEC
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if (!error)
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--
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2.7.4
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