[ARM] 4646/1: AT91: configurable HZ, default to 128
This makes HZ configurable on AT91, following the model used on OMAP. It defaults to a power of two on AT91rm9200 chips, avoiding rounding errors which come from dividing a 32 KiHz clock to generate scheduler irqs; and uses 100 on AT91sam926x chips, using MCK/16 (multi-MHZ). Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Remy Bhmer <linux@bohmer.net> Acked-by: Andrew Victor <andrew@sanpeople.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
parent
156864f806
commit
5248c65789
|
@ -657,6 +657,7 @@ config HZ
|
|||
default 128 if ARCH_L7200
|
||||
default 200 if ARCH_EBSA110 || ARCH_S3C2410
|
||||
default OMAP_32K_TIMER_HZ if ARCH_OMAP && OMAP_32K_TIMER
|
||||
default AT91_TIMER_HZ if ARCH_AT91
|
||||
default 100
|
||||
|
||||
config AEABI
|
||||
|
|
|
@ -219,6 +219,22 @@ config AT91_PROGRAMMABLE_CLOCKS
|
|||
Select this if you need to program one or more of the PCK0..PCK3
|
||||
programmable clock outputs.
|
||||
|
||||
config AT91_TIMER_HZ
|
||||
int "Kernel HZ (jiffies per second)"
|
||||
range 32 1024
|
||||
depends on ARCH_AT91
|
||||
default "128" if ARCH_AT91RM9200
|
||||
default "100"
|
||||
help
|
||||
On AT91rm9200 chips where you're using a system clock derived
|
||||
from the 32768 Hz hardware clock, this tick rate should divide
|
||||
it exactly: use a power-of-two value, such as 128 or 256, to
|
||||
reduce timing errors caused by rounding.
|
||||
|
||||
On AT91sam926x chips, or otherwise when using a higher precision
|
||||
system clock (of at least several MHz), rounding is less of a
|
||||
problem so it can be safer to use a decimal values like 100.
|
||||
|
||||
endmenu
|
||||
|
||||
endif
|
||||
|
|
Loading…
Reference in a new issue