174 lines
5.1 KiB
Diff
174 lines
5.1 KiB
Diff
From edeae90d635501a632efa0c7fe0667aa2cbe29be Mon Sep 17 00:00:00 2001
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From: Arjan van de Ven <arjan@linux.intel.com>
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Date: Mon, 28 Sep 2009 15:14:04 +0200
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Subject: [PATCH] acpi: Provide a set of tables to check the BIOS tables for correctness
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Today, the BIOS provides us with latency information for each C state.
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Unfortunately this information is sometimes put into the BIOS by
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apprentice BIOS programmers in a hurry, and as a result, it occasionally
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contains utter garbage.
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This patch adds a table based verification; if the CPU is known in the table,
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the values the BIOS provides to us are corrected for the apprentice-factor
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so that the CPUIDLE code can rely on the latency and break-even values
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to be reasonably sane.
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Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
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---
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drivers/acpi/Makefile | 2 +-
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drivers/acpi/processor_idle.c | 3 +
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drivers/acpi/processor_mwait_table.c | 110 ++++++++++++++++++++++++++++++++++
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include/acpi/processor.h | 3 +
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4 files changed, 117 insertions(+), 1 deletions(-)
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create mode 100644 drivers/acpi/processor_mwait_table.c
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diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
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index 82cd49d..ab56b28 100644
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--- a/drivers/acpi/Makefile
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+++ b/drivers/acpi/Makefile
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@@ -60,5 +60,5 @@ obj-$(CONFIG_ACPI_POWER_METER) += power_meter.o
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# processor has its own "processor." module_param namespace
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processor-y := processor_core.o processor_throttling.o
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-processor-y += processor_idle.o processor_thermal.o
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+processor-y += processor_idle.o processor_thermal.o processor_mwait_table.o
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processor-$(CONFIG_CPU_FREQ) += processor_perflib.o
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diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
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index cc61a62..db444a0 100644
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--- a/drivers/acpi/processor_idle.c
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+++ b/drivers/acpi/processor_idle.c
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@@ -1088,6 +1088,9 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
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state->target_residency = cx->latency * latency_factor;
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state->power_usage = cx->power;
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+ if (cx->entry_method == ACPI_CSTATE_FFH)
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+ acpi_verify_mwait_data(state, cx);
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+
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state->flags = 0;
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switch (cx->type) {
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case ACPI_STATE_C1:
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diff --git a/drivers/acpi/processor_mwait_table.c b/drivers/acpi/processor_mwait_table.c
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new file mode 100644
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index 0000000..f29c28c
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--- /dev/null
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+++ b/drivers/acpi/processor_mwait_table.c
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@@ -0,0 +1,102 @@
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+/*
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+ * processor_mwait_table.c: BIOS table verification/correction
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+ *
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+ * (C) Copyright 2009 Intel Corporation
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+ * Authors:
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+ * Arjan van de Ven <arjan@linux.intel.com>
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License
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+ * as published by the Free Software Foundation; version 2
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+ * of the License.
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+ */
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+
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+#include <asm/processor.h>
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+#include <linux/acpi.h>
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+#include <acpi/processor.h>
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+#include <linux/cpuidle.h>
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+
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+
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+#define ATLEAST 1
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+#define ATMOST 2
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+#define EXACTLY 3
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+
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+#define MAX_ENTRIES 12
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+
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+struct mwait_entry {
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+ unsigned int mwait_value;
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+ unsigned long exit_latency;
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+ unsigned long break_even_point;
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+ int compare_method;
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+};
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+
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+struct cpu_entry {
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+ int vendor;
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+ int family;
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+ int model;
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+
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+ struct mwait_entry entries[MAX_ENTRIES];
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+};
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+
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+static struct cpu_entry mwait_entries[] =
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+{
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+ /* Intel "Atom" CPUs */
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+ {.vendor = X86_VENDOR_INTEL, .family = 6, . model = 28,
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+ .entries = {
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+ {0x00, 1, 1, ATLEAST},
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+ {0x10, 2, 20, ATLEAST},
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+ {0x30, 57, 300, ATLEAST},
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+ {0x50, 64, 4000, ATLEAST},
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+ }
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+ },
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+
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+
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+};
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+
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+
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+static unsigned long
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+compare_and_set(unsigned long original, unsigned long new, int compare)
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+{
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+ if (compare == EXACTLY)
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+ return new;
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+ if (compare == ATLEAST && new > original)
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+ return new;
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+ if (compare == ATMOST && new < original)
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+ return new;
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+ return original;
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+}
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+
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+
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+void acpi_verify_mwait_data(struct cpuidle_state *state,
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+ struct acpi_processor_cx *cx)
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+{
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+#if defined(__i386__) || defined(__x86_64__)
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+ int i;
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+
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+ struct cpuinfo_x86 *cpudata = &boot_cpu_data;
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+
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+
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+ for (i = 0; i < ARRAY_SIZE(mwait_entries); i++) {
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+ int j;
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+ if (mwait_entries[i].vendor != cpudata->x86_vendor)
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+ continue;
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+ if (mwait_entries[i].family != cpudata->x86)
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+ continue;
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+ if (mwait_entries[i].model != cpudata->x86_model)
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+ continue;
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+ for (j = 0; j < ARRAY_SIZE(mwait_entries[i].entries); j++) {
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+ if (!mwait_entries[i].entries[j].compare_method)
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+ continue;
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+ if (mwait_entries[i].entries[j].mwait_value != cx->address)
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+ continue;
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+ state->exit_latency = compare_and_set(state->exit_latency,
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+ mwait_entries[i].entries[j].exit_latency,
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+ mwait_entries[i].entries[j].compare_method);
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+ state->target_residency = compare_and_set(state->target_residency,
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+ mwait_entries[i].entries[j].break_even_point,
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+ mwait_entries[i].entries[j].compare_method);
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+ break;
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+ }
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+ }
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+#endif
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+}
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diff --git a/include/acpi/processor.h b/include/acpi/processor.h
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index 740ac3a..175e4d1 100644
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--- a/include/acpi/processor.h
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+++ b/include/acpi/processor.h
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@@ -352,5 +352,8 @@ static inline void acpi_thermal_cpufreq_exit(void)
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return;
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}
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#endif
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+extern void acpi_verify_mwait_data(struct cpuidle_state *state,
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+ struct acpi_processor_cx *cx);
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+
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#endif
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--
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1.6.2.5
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