ARM: 6488/1: nomadik: prevent sched_clock() wraparound

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The current implementation of sched_clock() for the Nomadik
family is based on the clock source that will wrap around without
any compensation. Currently on the Ux500 after 1030 seconds.

Utilize cnt32_to_63 to expand the sched_clock() counter to 63
bits and introduce a keepwarm() timer to assure that sched clock
and this cnt32_to_63 is called atleast once every half period.

When I print out the actual wrap-around time, and using
a year (3600*24*365 seconds) as minumum wrap limit I get an
actual wrap-around of:
sched_clock: using 55 bits @ 8333125 Hz wrap in 416 days

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

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Linus Walleij 2010-11-19 10:16:05 +01:00 • committed by Russell King

parent 963fec4e0f

commit 8fbb97a2bc

1 changed files with 80 additions and 9 deletions

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arch/arm/plat-nomadik/timer.c

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