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@lists.linaro.org [mailto:linaro-dev-bounces@lists.linaro.org] On Behalf Of John Stultz Sent: Wednesday, February 08, 2012 6:09 PM To: Andrew Richardson Cc: linux-omap@vger.kernel.org; linaro-dev@lists.linaro.org 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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