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tools, update rtctest.c to verify passage of time

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rtctest.c checks to see if PIE is functioning by testing if 20 interrupts occur
at rates from 2HZ to 64HZ.  While this check is good, it does not check to
see if the correct amount of time has actually passed.  This misses
situations where the RTC may be operating at a higher or lower frequency
than expected.

This patch introduces a simple check to verify if the time passed is
less than 10% of what was programmed into the RTC.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: corbet@lwn.net
Cc: rtc-linux@googlegroups.com
Cc: linux-doc@vger.kernel.org
Cc: a.zummo@towertech.it
Cc: prarit@redhat.com
Cc: john.stultz@linaro.org
Cc: shuahkh@osg.samsung.com
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
This commit is contained in:
Prarit Bhargava 2015-03-18 15:46:33 -04:00 committed by Shuah Khan
parent 4a5fd81507
commit 0b63accf87
1 changed files with 13 additions and 0 deletions
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13
tools/testing/selftests/timers/rtctest.c
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@ -36,6 +36,7 @@ int main(int argc, char **argv)
unsigned long tmp, data;
struct rtc_time rtc_tm;
const char *rtc = default_rtc;
struct timeval start, end, diff;
switch (argc) {
case 2:
@ -230,12 +231,24 @@ test_PIE:
}
for (i=1; i<21; i++) {
gettimeofday(&start, NULL);
/* This blocks */
retval = read(fd, &data, sizeof(unsigned long));
if (retval == -1) {
perror("read");
exit(errno);
}
gettimeofday(&end, NULL);
timersub(&end, &start, &diff);
if (diff.tv_sec > 0 ||
diff.tv_usec > ((1000000L / tmp) * 1.10)) {
fprintf(stderr, "\nPIE delta error: %ld.%06ld should be close to 0.%06ld\n",
diff.tv_sec, diff.tv_usec,
(1000000L / tmp));
fflush(stdout);
exit(-1);
}
fprintf(stderr, " %d",i);
fflush(stderr);
irqcount++;