oberg_at_isy <> [2010-03-08 12:43:31]:
> Hi everyone
Hi,
> In linux/arch/arm/mach-ep93xx/core.c EP93XX_TIMER1_LOAD is loaded with
> "(508469 / HZ) - 1" to obtain a timer with the HZ frequency. Timer 1 is
> running at 508 kHz so this seems strange. On the other hand HZ is 100 so the
> last parts of the load-value is thrown away.
well, it's not exactly 508 kHz as the docs claims, but it's 14.7456 Mhz
divided by 29 = 508496. The timer is 16-bit only, you can't feed it with this
value anyway.
> Is there a reason for this?
Yes, it's CONFIG_HZ value, it's a frequency of the timer interrupt, so if it's
100, it means, that it will be called 1/100 of second, or 10ms. So if you feed
it with 508496 it will be called once a second, which is wrong since the timer
interrupt is heart of the system. So the value 5083 is correct and means the
timer interrupt is called 100 times per second, every 10ms.
-- ynezz
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