powerpc: Fix decrementer setup on 1GHz boards

Browse source

We noticed that recent kernels didn't boot on our 1GHz Canyonlands 460EX
boards anymore. As it seems, patch 8d165db1 [powerpc: Improve
decrementer accuracy] introduced this problem. The routine div_sc()
overflows with shift = 32 resulting in this incorrect setup:

time_init: decrementer frequency = 1000.000012 MHz
time_init: processor frequency   = 1000.000012 MHz
clocksource: timebase mult[400000] shift[22] registered
clockevent: decrementer mult[33] shift[32] cpu[0]

This patch now introduces a local div_dc64() version of this function
so that this overflow doesn't happen anymore.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Detlev Zundel <dzu@denx.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

...

This commit is contained in:

Stefan Roese 2010-01-11 22:28:54 +00:00 • committed by Benjamin Herrenschmidt

parent b0ff153cd6

commit 3e7b484354

1 changed files with 10 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

11

arch/powerpc/kernel/time.c

View file