On Thu, Apr 17, 2008 at 04:52:35PM +0400, Anton Vorontsov wrote:
> Heh. Scott, think about it. You have single 16bit timer with variable
> frequency. To use it, you'd better know what exactly precision you need.
Why? I know the timeout I need.
> Then you limited to u16 for the interval for this chosen precision.
>
> Yes, you can implement this:
>
> #define MAX_PRESCALER (256 * 256 * 16)
>
> int gtm_reset_weird_behaving_utimer16(struct gtm_timer *tmr,
> unsigned long long usec,
> bool free_run)
> {
> int freq = 1000000;
> int min_hz2 = (tmr->gtm->freq / MAX_PRESCALER) << 1;
>
> while (!(freq & 1) && !(usec & 1) && freq >= min_hz2) {
> freq >>= 1;
> usec >>= 1;
> }
>
> if (usec > 0xffff)
> return -EINVAL;
>
> return gtm_reset_ref_timer16(tmr, freq, (u16)usec, free_run);
> }
Try something like this:
int gtm_reset_sane_behaving_timer(struct gtm_timer *tmr,
u64 usec, bool free_run)
{
int freq = 1000000;
int min_hz2 = (tmr->gtm->freq / MAX_PRESCALER) << 1;
while (usec > 0xffff && freq >= min_hz2) {
freq >>= 1;
usec >>= 1;
}
if (usec > 0xffff)
return -EINVAL;
return gtm_reset_ref_timer16(tmr, freq, usec, free_run);
}
It could be made faster using cntlzw.
-Scott
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@ozlabs.org
https://ozlabs.org/mailman/listinfo/linuxppc-dev
