diff options
Diffstat (limited to 'arch/i386/kernel/cpu/cpufreq/speedstep-lib.c')
| -rw-r--r-- | arch/i386/kernel/cpu/cpufreq/speedstep-lib.c | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/arch/i386/kernel/cpu/cpufreq/speedstep-lib.c b/arch/i386/kernel/cpu/cpufreq/speedstep-lib.c index d368b3f5fce8..7c47005a1805 100644 --- a/arch/i386/kernel/cpu/cpufreq/speedstep-lib.c +++ b/arch/i386/kernel/cpu/cpufreq/speedstep-lib.c @@ -320,11 +320,13 @@ EXPORT_SYMBOL_GPL(speedstep_detect_processor); unsigned int speedstep_get_freqs(unsigned int processor, unsigned int *low_speed, unsigned int *high_speed, + unsigned int *transition_latency, void (*set_state) (unsigned int state)) { unsigned int prev_speed; unsigned int ret = 0; unsigned long flags; + struct timeval tv1, tv2; if ((!processor) || (!low_speed) || (!high_speed) || (!set_state)) return -EINVAL; @@ -337,7 +339,7 @@ unsigned int speedstep_get_freqs(unsigned int processor, return -EIO; dprintk("previous speed is %u\n", prev_speed); - + local_irq_save(flags); /* switch to low state */ @@ -350,8 +352,17 @@ unsigned int speedstep_get_freqs(unsigned int processor, dprintk("low speed is %u\n", *low_speed); + /* start latency measurement */ + if (transition_latency) + do_gettimeofday(&tv1); + /* switch to high state */ set_state(SPEEDSTEP_HIGH); + + /* end latency measurement */ + if (transition_latency) + do_gettimeofday(&tv2); + *high_speed = speedstep_get_processor_frequency(processor); if (!*high_speed) { ret = -EIO; @@ -369,6 +380,25 @@ unsigned int speedstep_get_freqs(unsigned int processor, if (*high_speed != prev_speed) set_state(SPEEDSTEP_LOW); + if (transition_latency) { + *transition_latency = (tv2.tv_sec - tv1.tv_sec) * USEC_PER_SEC + + tv2.tv_usec - tv1.tv_usec; + dprintk("transition latency is %u uSec\n", *transition_latency); + + /* convert uSec to nSec and add 20% for safety reasons */ + *transition_latency *= 1200; + + /* check if the latency measurement is too high or too low + * and set it to a safe value (500uSec) in that case + */ + if (*transition_latency > 10000000 || *transition_latency < 50000) { + printk (KERN_WARNING "speedstep: frequency transition measured seems out of " + "range (%u nSec), falling back to a safe one of %u nSec.\n", + *transition_latency, 500000); + *transition_latency = 500000; + } + } + out: local_irq_restore(flags); return (ret); |