Messages in this thread |  | | | Date | Wed, 5 May 2010 22:25:29 +0200 | | From | Uwe Kleine-König <> | | Subject | Re: [at91] Save power by disabling the processor clock when CPU is idle |
| |
Hello,
On Tue, Apr 13, 2010 at 01:05:32PM +0200, Anders Larsen wrote: > Disable the processor clock when the CPU is idle. > > This saves much more power than merely entering 'Wait for Interrupt' mode. > Since JTAG-debugging doesn't work when the processor clock is switched off, > make it conditional on CONFIG_DEBUG_KERNEL. > > Signed-off-by: Anders Larsen <al@alarsen.net> > Cc: Andrew Victor <avictor.za@gmail.com> > --- > KernelVersion: 2.6.33 > > arch/arm/mach-at91/include/mach/system.h | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > > Index: b/arch/arm/mach-at91/include/mach/system.h > =================================================================== > --- a/arch/arm/mach-at91/include/mach/system.h > +++ b/arch/arm/mach-at91/include/mach/system.h > @@ -24,21 +24,24 @@ > #include <mach/hardware.h> > #include <mach/at91_st.h> > #include <mach/at91_dbgu.h> > +#include <mach/at91_pmc.h> > > static inline void arch_idle(void) > { > +#ifndef CONFIG_DEBUG_KERNEL > /* > * Disable the processor clock. The processor will be automatically > * re-enabled by an interrupt or by a reset. > */ > -// at91_sys_write(AT91_PMC_SCDR, AT91_PMC_PCK); > - > + at91_sys_write(AT91_PMC_SCDR, AT91_PMC_PCK); > +#else > /* > * Set the processor (CP15) into 'Wait for Interrupt' mode. > * Unlike disabling the processor clock via the PMC (above) > * this allows the processor to be woken via JTAG. > */ > cpu_do_idle(); > +#endif
There is a kernel parameter (IIRC "nohlt") that should take care of this?!
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |