diff options
Diffstat (limited to 'drivers/misc/ioc4.c')
| -rw-r--r-- | drivers/misc/ioc4.c | 31 |
1 files changed, 16 insertions, 15 deletions
diff --git a/drivers/misc/ioc4.c b/drivers/misc/ioc4.c index 3336ddca45a..8758d033db2 100644 --- a/drivers/misc/ioc4.c +++ b/drivers/misc/ioc4.c @@ -144,9 +144,9 @@ ioc4_clock_calibrate(struct ioc4_driver_data *idd) { union ioc4_int_out int_out; union ioc4_gpcr gpcr; - unsigned int state, last_state = 1; + unsigned int state, last_state; uint64_t start, end, period; - unsigned int count = 0; + unsigned int count; /* Enable output */ gpcr.raw = 0; @@ -167,19 +167,20 @@ ioc4_clock_calibrate(struct ioc4_driver_data *idd) mmiowb(); /* Check square wave period averaged over some number of cycles */ - do { - int_out.raw = readl(&idd->idd_misc_regs->int_out.raw); - state = int_out.fields.int_out; - if (!last_state && state) { - count++; - if (count == IOC4_CALIBRATE_END) { - end = ktime_get_ns(); - break; - } else if (count == IOC4_CALIBRATE_DISCARD) - start = ktime_get_ns(); - } - last_state = state; - } while (1); + start = ktime_get_ns(); + state = 1; /* make sure the first read isn't a rising edge */ + for (count = 0; count <= IOC4_CALIBRATE_END; count++) { + do { /* wait for a rising edge */ + last_state = state; + int_out.raw = readl(&idd->idd_misc_regs->int_out.raw); + state = int_out.fields.int_out; + } while (last_state || !state); + + /* discard the first few cycles */ + if (count == IOC4_CALIBRATE_DISCARD) + start = ktime_get_ns(); + } + end = ktime_get_ns(); /* Calculation rearranged to preserve intermediate precision. * Logically: |