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ARM: ep93xx: update comment on timer usage 

When refactoring the EP93xx timer some of the documentation
git out of date. Update it.

Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
hifive-unleashed-5.1
Linus Walleij 2015-06-16 09:00:44 +02:00
parent d5878e6e22
commit 8ed3912e17
1 changed files with 6 additions and 7 deletions
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13
arch/arm/mach-ep93xx/timer-ep93xx.c
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@ -18,15 +18,14 @@
* is free-running, and can't generate interrupts.
*
* The 508 kHz timers are ideal for use for the timer interrupt, as the
* most common values of HZ divide 508 kHz nicely. We pick one of the 16
* bit timers (timer 1) since we don't need more than 16 bits of reload
* value as long as HZ >= 8.
* most common values of HZ divide 508 kHz nicely. We pick the 32 bit
* timer (timer 3) to get as long sleep intervals as possible when using
* CONFIG_NO_HZ.
*
* The higher clock rate of timer 4 makes it a better choice than the
* other timers for use in gettimeoffset(), while the fact that it can't
* generate interrupts means we don't have to worry about not being able
* to use this timer for something else. We also use timer 4 for keeping
* track of lost jiffies.
* other timers for use as clock source and for sched_clock(), providing
* a stable 40 bit time base.
*************************************************************************
*/
#define EP93XX_TIMER_REG(x) (EP93XX_TIMER_BASE + (x))
#define EP93XX_TIMER1_LOAD EP93XX_TIMER_REG(0x00)