On Monday 11 May 2015 08:02:57 Tina Ruchandani wrote:
do_gettimeofday(&tv_now);elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;elapsed_8000th = (tv_now.tv_usec / 125)- (iclock_tv.tv_usec / 125);if (elapsed_8000th < 0) {elapsed_sec -= 1;elapsed_8000th += 8000;}
tv_now = ktime_get();
A minor coding style comment here: If you have a multi-line block after if() using curly braces, then you should also use that for the else path, even if that is just one line.
However, if both sides do not need curly braces, leave them out entirely.
delta = ktime_to_us(ktime_sub(tv_now, iclock_tv));
We have a ktime_us_delta() function now that would simplify this slightly.
delta = delta / 125;
This looks like a possible bug: delta is a 16-bit number, so it will be truncated to 65536 microseconds when assigning the result of ktime_us_delta() or ktime_to_us(), and then you divide by 125, so it will now be a number that is smaller than 524, and if the elapsed time is more than 65536 microseconds, you can an incorrect result.
You can avoid that by using a 32-bit temporary, or doing it implicitly as
delta = ktime_us_delta(tv_now, iclock_tv) / 125;
Another option would be to calculate the right number from the nanoseconds:
delta = ktime_divns(ktime_sub(tv_now, iclock_tv), (NS_PER_SEC / 8000));
Arnd