diff options
Diffstat (limited to 'libdde_linux26')
| -rw-r--r-- | libdde_linux26/lib/src/init/calibrate.c | 78 |
1 files changed, 48 insertions, 30 deletions
diff --git a/libdde_linux26/lib/src/init/calibrate.c b/libdde_linux26/lib/src/init/calibrate.c index aede8e53..687da473 100644 --- a/libdde_linux26/lib/src/init/calibrate.c +++ b/libdde_linux26/lib/src/init/calibrate.c @@ -123,11 +123,50 @@ static unsigned long __cpuinit calibrate_delay_direct(void) {return 0;} */ #define LPS_PREC 8 -void __cpuinit calibrate_delay(void) +static unsigned long __cpuinit calibrate_delay_estimate(void) { unsigned long ticks, loopbit; int lps_precision = LPS_PREC; + int loops_per_jiffy; + + loops_per_jiffy = (1<<12); + + while ((loops_per_jiffy <<= 1) != 0) { + /* wait for "start of" clock tick */ + ticks = jiffies; + while (ticks == jiffies) + /* nothing */; + /* Go .. */ + ticks = jiffies; + __delay(loops_per_jiffy); + ticks = jiffies - ticks; + if (ticks) + break; + } + + /* + * Do a binary approximation to get loops_per_jiffy set to + * equal one clock (up to lps_precision bits) + */ + loops_per_jiffy >>= 1; + loopbit = loops_per_jiffy; + while (lps_precision-- && (loopbit >>= 1)) { + loops_per_jiffy |= loopbit; + ticks = jiffies; + while (ticks == jiffies) + /* nothing */; + ticks = jiffies; + __delay(loops_per_jiffy); + if (jiffies != ticks) /* longer than 1 tick */ + loops_per_jiffy &= ~loopbit; + } + return loops_per_jiffy; +} +#define NRETRIES 3 + +void __cpuinit calibrate_delay(void) +{ if (preset_lpj) { loops_per_jiffy = preset_lpj; printk(KERN_INFO @@ -141,38 +180,17 @@ void __cpuinit calibrate_delay(void) printk(KERN_INFO "Calibrating delay using timer specific routine.. "); } else { - loops_per_jiffy = (1<<12); + int i; + unsigned long result; printk(KERN_INFO "Calibrating delay loop... "); - while ((loops_per_jiffy <<= 1) != 0) { - /* wait for "start of" clock tick */ - ticks = jiffies; - while (ticks == jiffies) - /* nothing */; - /* Go .. */ - ticks = jiffies; - __delay(loops_per_jiffy); - ticks = jiffies - ticks; - if (ticks) - break; - } - - /* - * Do a binary approximation to get loops_per_jiffy set to - * equal one clock (up to lps_precision bits) - */ - loops_per_jiffy >>= 1; - loopbit = loops_per_jiffy; - while (lps_precision-- && (loopbit >>= 1)) { - loops_per_jiffy |= loopbit; - ticks = jiffies; - while (ticks == jiffies) - /* nothing */; - ticks = jiffies; - __delay(loops_per_jiffy); - if (jiffies != ticks) /* longer than 1 tick */ - loops_per_jiffy &= ~loopbit; + loops_per_jiffy = 0; + for (i = 0; i < NRETRIES; i++) { + result = calibrate_delay_estimate(); + if (result > loops_per_jiffy) + loops_per_jiffy = result; } + } printk(KERN_CONT "%lu.%02lu BogoMIPS (lpj=%lu)\n", loops_per_jiffy/(500000/HZ), |