Messages in this thread | | | Date | Wed, 13 Sep 2006 14:33:49 -0500 | From | Ryan Underwood <> | Subject | odd cpu_khz behavior (doubling) |
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OK, I realize cpu_khz should not be constant. I wrote a cpufreq driver for Toshiba laptops that has two CPU speeds (1/2 and full) and that is managed via SMM. Can anyone tell me why cpu_khz occasionally doubles itself while the driver is in use? It starts at ~120000, then doubles to ~240000, then to ~480000, etc. However, this is over ~15 loads and unloads of the cpufreq target driver. Small cpu_khz variations would not bother anything wrt the cpufreq driver, but this is just plain incorrect for things like /proc/cpuinfo which also use cpu_khz.
Is this a TSC issue (maybe related to SMM) or am I just doing something in the wrong place in the driver?
Attached is the cpufreq part of the code, just a testing version.
-- Ryan Underwood, <nemesis@icequake.net> /* * toshiba_freq.c: cpufreq driver for Toshiba SCI (non-Speedstep) laptops * * Copyright (C) 2006 Ryan Underwood <nemesis@icequake.net> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Based on sc520_freq.c * * 2006-09-11: - initial revision */
/* NOTE: currently this should drag in toshiba.ko which checks for the * appropriate hardware in its init function. Things will be different when * ACPI instead of the SMM driver is used as the SCI access method. */
/* XXX, error handling on all tosh_scihci calls!! And graceful exit! */ /* FIXME: Fan and LCD brightness are variable on some systems */
#include <linux/kernel.h> #include <linux/module.h> #include <linux/init.h>
#include <linux/cpufreq.h> #include <linux/toshiba.h>
#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "toshiba_freq", msg)
static u32 original_cpustate; static u32 original_cache; static u32 original_brightness; static u32 original_fan;
/* Store this locally to avoid a SMM round trip to obtain it */ static u32 current_cpustate;
static int control_cpucache = 1; static int control_fan = 1; static int control_lcd;
module_param_named(cpucache, control_cpucache, int, 1); MODULE_PARM_DESC(fn, "Allow CPUFreq to enable/disable CPU cache"); module_param_named(fan, control_fan, int, 1); MODULE_PARM_DESC(fn, "Allow CPUFreq to control the system fan"); module_param_named(lcd, control_lcd, int, 0); MODULE_PARM_DESC(fn, "Allow CPUFreq to control LCD brightness");
/* Index corresponds to the SCI CPU speed state (0 or 1) */ static struct cpufreq_frequency_table toshiba_freq_table[] = { {0, 0}, /* slow (low) */ {1, 0}, /* fast (high) */ {0, CPUFREQ_TABLE_END}, };
static unsigned int toshiba_freq_get_cpu_frequency(unsigned int cpu) { #if 0 unsigned int val; tosh_scihci_get(0, SCI_PROCESSING, &val); return val; #else return toshiba_freq_table[current_cpustate].frequency; #endif }
static void toshiba_freq_set_cpu_state (unsigned int state) { struct cpufreq_freqs freqs;
freqs.old = toshiba_freq_get_cpu_frequency(0); freqs.new = toshiba_freq_table[state].frequency; freqs.cpu = 0;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
dprintk("attempting to set frequency to %i kHz\n", toshiba_freq_table[state].frequency);
if (state == 0) { /* slow */ if (control_fan) tosh_scihci_set(HCI_SET, HCI_FAN, HCI_DISABLE); if (control_lcd) tosh_scihci_set(0, SCI_LCD_BRIGHTNESS, SCI_SEMI_BRIGHT); if (control_cpucache) tosh_scihci_set(0, SCI_CPU_CACHE, SCI_OFF); tosh_scihci_set(0, SCI_PROCESSING, SCI_LOW); } else { /* fast */ if (control_fan) tosh_scihci_set(HCI_SET, HCI_FAN, HCI_ENABLE); if (control_lcd) tosh_scihci_set(0, SCI_LCD_BRIGHTNESS, SCI_BRIGHT); if (control_cpucache) tosh_scihci_set(0, SCI_CPU_CACHE, SCI_ON); tosh_scihci_set(0, SCI_PROCESSING, SCI_HIGH); }
current_cpustate = toshiba_freq_table[state].index;
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); };
static int toshiba_freq_verify (struct cpufreq_policy *policy) { return cpufreq_frequency_table_verify(policy, &toshiba_freq_table[0]); }
static int toshiba_freq_target (struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) { unsigned int newstate = 0;
if (cpufreq_frequency_table_target(policy, toshiba_freq_table, target_freq, relation, &newstate)) return -EINVAL;
toshiba_freq_set_cpu_state(newstate);
return 0; }
/* * Module init and exit code */
static int toshiba_freq_cpu_init(struct cpufreq_policy *policy) { int result;
/* Fill out the frequency table * Toshiba SCI has two modes, "slow" and "fast" where "fast" is * the nominal CPU speed, and "slow" is half speed */
/* Prevent userspace from using /dev/toshiba to frob the CPU speed */ tosh_cpufreq_in_control = 1;
/* It would be nice if we could obtain the CPU nominal MHz rating from * the firmware somehow. Oh well. We use cpu_khz instead since it is * close enough for our needs. */
/* FIXME why is cpu_khz doubling? */ toshiba_freq_table[0].frequency = cpu_khz / 2; toshiba_freq_table[1].frequency = cpu_khz;
/* cpuinfo and default policy values */ policy->governor = CPUFREQ_DEFAULT_GOVERNOR; policy->cpuinfo.transition_latency = 5000000; /* 5ms, estimated max SMI/SMM latency */ policy->cur = toshiba_freq_get_cpu_frequency(0);
result = cpufreq_frequency_table_cpuinfo(policy, toshiba_freq_table); if (result) return (result);
cpufreq_frequency_table_get_attr(toshiba_freq_table, policy->cpu);
return 0; }
static int toshiba_freq_cpu_exit(struct cpufreq_policy *policy) { cpufreq_frequency_table_put_attr(policy->cpu); /* Restore the old configuration */ if (control_fan) tosh_scihci_set(HCI_SET, HCI_FAN, original_fan);
if (control_lcd) tosh_scihci_set(0, SCI_LCD_BRIGHTNESS, original_brightness);
if (control_cpucache) tosh_scihci_set(0, SCI_CPU_CACHE, original_cache);
tosh_scihci_set(0, SCI_PROCESSING, original_cpustate);
/* Allow userspace to control CPU via SCI again */ tosh_cpufreq_in_control = 0;
return 0; }
static struct freq_attr* toshiba_freq_attr[] = { &cpufreq_freq_attr_scaling_available_freqs, NULL, };
static struct cpufreq_driver toshiba_freq_driver = { .get = toshiba_freq_get_cpu_frequency, .verify = toshiba_freq_verify, .target = toshiba_freq_target, .init = toshiba_freq_cpu_init, .exit = toshiba_freq_cpu_exit, .name = "toshiba_freq", .owner = THIS_MODULE, .attr = toshiba_freq_attr, };
static int __init toshiba_freq_init(void) { /* Note: At least some ACPI machines do not allow the SMM driver to * modify the CPU frequency. Here, we will read all the settings we * are interested in and attempt to set their values, as a test that we * are actually in control of the hardware. */
char buf[100];
/* CPU speed state */ if (tosh_scihci_get(0, SCI_PROCESSING, &original_cpustate) || tosh_scihci_set(0, SCI_PROCESSING, original_cpustate)) return -ENODEV;
sprintf(buf, "toshiba_freq.c: Managing CPU");
/* CPU cache */ if (control_cpucache) { if (tosh_scihci_get(0, SCI_CPU_CACHE, &original_cache) || tosh_scihci_set(0, SCI_CPU_CACHE, original_cache)) return -ENODEV; strcat(buf, ", L2 cache"); }
/* Fan */ if (control_fan) { if (tosh_scihci_get(HCI_GET, HCI_FAN, &original_fan) || tosh_scihci_set(HCI_SET, HCI_FAN, original_fan)) return -ENODEV; strcat(buf, ", system fan"); }
/* Display brightness */ if (control_lcd) { if (tosh_scihci_get(0, SCI_LCD_BRIGHTNESS, &original_brightness) || tosh_scihci_set(0, SCI_LCD_BRIGHTNESS, original_brightness)) return -ENODEV; strcat(buf, ", LCD"); }
printk("%s\n", buf);
current_cpustate = original_cpustate;
return cpufreq_register_driver(&toshiba_freq_driver); }
static void __exit toshiba_freq_exit(void) { cpufreq_unregister_driver(&toshiba_freq_driver); }
MODULE_LICENSE("GPL"); MODULE_AUTHOR("Ryan Underwood <nemesis@icequake.net>"); MODULE_DESCRIPTION("cpufreq driver for Toshiba SCI (non-Speedstep) laptops");
module_init(toshiba_freq_init); module_exit(toshiba_freq_exit);
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