Hi,
Never had any issue with 32K and gettimeofday() on Panda (but just starting to use clock_gettime()). It was used to timestamp events happening every few ms or 100s of us.
I would advise as a check:
- read clock_gettime()/gettimeofday() and in parallel 32K register (map and read physical address 0x4A304010) to check behaviour.
- There is potential issue (that we have never seen) when reading 32K register. Worked around by calling clock_gettime()/gettimeofday() twice (we never do that and still it works so ...)
We have been doing tests in the past like while(1) {gettimeofday(); printf("time ...")} and it worked correctly, exhibiting the 30.5us accuracy
Regards
Fred
Texas Instruments France SA, 821 Avenue Jack Kilby, 06270 Villeneuve Loubet. 036 420 040 R.C.S Antibes. Capital de EUR 753.920
-----Original Message-----
From: linaro-dev-bounces@xxxxxxxxxxxxxxxx [mailto:linaro-dev-bounces@xxxxxxxxxxxxxxxx] On Behalf Of John Stultz
Sent: Wednesday, February 08, 2012 6:09 PM
To: Andrew Richardson
Cc: linux-omap@xxxxxxxxxxxxxxx; linaro-dev@xxxxxxxxxxxxxxxx
Subject: Re: Minimum timing resolution in Ubuntu/Linaro on the PandaBoard ES
On Wed, 2012-02-08 at 04:32 -0500, Andrew Richardson wrote:
> Ah, very interesting.
> > dmesg | grep clock
> [ 0.000000] OMAP clockevent source: GPTIMER1 at 32768 Hz
> [ 0.000000] sched_clock: 32 bits at 32kHz, resolution
> 30517ns, wraps every 131071999ms
Hrm. So 30us is still much smaller then the 2.5ms you were seeing. So
that doesn't fully explain the behavior.
thanks
-john
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