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Allow users to reject levels below a given frequency (in MHz) via the

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debug.cpufreq.lowest tunable and sysctl.  Some systems seem to have problems
with the lowest frequencies so setting this prevents them from being
available or used.
This commit is contained in:
Nate Lawson 2005-02-26 22:37:49 +00:00
parent 4bb8b8beda
commit b070969b48
1 changed files with 17 additions and 1 deletions
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18
sys/kern/kern_cpu.c
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@ -109,7 +109,13 @@ static driver_t cpufreq_driver = {
static devclass_t cpufreq_dc;
DRIVER_MODULE(cpufreq, cpu, cpufreq_driver, cpufreq_dc, 0, 0);
static eventhandler_tag cf_ev_tag;
static eventhandler_tag cf_ev_tag;
static int cf_lowest_freq;
TUNABLE_INT("debug.cpufreq.lowest", &cf_lowest_freq);
SYSCTL_NODE(_debug, OID_AUTO, cpufreq, CTLFLAG_RD, NULL, "cpufreq debugging");
SYSCTL_INT(_debug_cpufreq, OID_AUTO, lowest, CTLFLAG_RW, &cf_lowest_freq, 1,
"Don't provide levels below this frequency.");
static int
cpufreq_attach(device_t dev)
@ -206,6 +212,10 @@ cf_set_method(device_t dev, const struct cf_level *level, int priority)
} else if (priority < sc->curr_priority)
return (EPERM);
/* Reject levels that are below our specified threshold. */
if (level->total_set.freq <= cf_lowest_freq)
return (EINVAL);
/* If already at this level, just return. */
if (CPUFREQ_CMP(sc->curr_level.total_set.freq, level->total_set.freq))
return (0);
@ -474,6 +484,12 @@ cf_levels_method(device_t dev, struct cf_level *levels, int *count)
/* Finally, output the list of levels. */
i = 0;
TAILQ_FOREACH(lev, &sc->all_levels, link) {
/* Skip levels that have a frequency that is too low. */
if (lev->total_set.freq <= cf_lowest_freq) {
sc->all_count--;
continue;
}
levels[i] = *lev;
i++;
}