[PATCH] arm: omap4: allow disabling MPU local timer if 32K timer is enabled
With 32K gp timer, tick can be driven and system can run well, so allow MPU local timer to be disabled if someone requires it, otherwise MPU local timer is always chosen as the default clock_event_device. Signed-off-by: Ming Lei tom.leim...@gmail.com --- arch/arm/mach-omap2/Kconfig |2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig index d965da4..12cd602 100644 --- a/arch/arm/mach-omap2/Kconfig +++ b/arch/arm/mach-omap2/Kconfig @@ -46,7 +46,7 @@ config ARCH_OMAP4 select CPU_V7 select ARM_GIC select HAVE_SMP - select LOCAL_TIMERS if SMP + select LOCAL_TIMERS if (SMP !OMAP_32K_TIMER) select PL310_ERRATA_588369 select PL310_ERRATA_727915 select ARM_ERRATA_720789 -- 1.7.9 -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] arm: omap4: allow disabling MPU local timer if 32K timer is enabled
On Sat, Feb 11, 2012 at 04:31:25PM +0800, Ming Lei wrote: With 32K gp timer, tick can be driven and system can run well, so allow MPU local timer to be disabled if someone requires it, otherwise MPU local timer is always chosen as the default clock_event_device. The point being? What if you want to use NO_HZ? -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] arm: omap4: allow disabling MPU local timer if 32K timer is enabled
On Sat, Feb 11, 2012 at 6:03 PM, Russell King - ARM Linux li...@arm.linux.org.uk wrote: On Sat, Feb 11, 2012 at 04:31:25PM +0800, Ming Lei wrote: With 32K gp timer, tick can be driven and system can run well, so allow MPU local timer to be disabled if someone requires it, otherwise MPU local timer is always chosen as the default clock_event_device. The point being? IMO, 32K gp timer may be more energy-saving than MPU local timer because gp timer has much less clock frequency and only half interrupts generated in tick mode compared with mpu local timer. What if you want to use NO_HZ? 32K gp timer supports oneshot mode, so it should support NO_HZ. In my test .config, NO_HZ is enabled and system can run well. thanks, -- Ming Lei -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] arm: omap4: allow disabling MPU local timer if 32K timer is enabled
On Sat, Feb 11, 2012 at 06:19:41PM +0800, Ming Lei wrote: On Sat, Feb 11, 2012 at 6:03 PM, Russell King - ARM Linux li...@arm.linux.org.uk wrote: On Sat, Feb 11, 2012 at 04:31:25PM +0800, Ming Lei wrote: With 32K gp timer, tick can be driven and system can run well, so allow MPU local timer to be disabled if someone requires it, otherwise MPU local timer is always chosen as the default clock_event_device. The point being? IMO, 32K gp timer may be more energy-saving than MPU local timer because gp timer has much less clock frequency and only half interrupts generated in tick mode compared with mpu local timer. What if you want to use NO_HZ? 32K gp timer supports oneshot mode, so it should support NO_HZ. In my test .config, NO_HZ is enabled and system can run well. Have you actually checked the tick rate of your timer in /proc/interrupts? Have you checked /proc/timer_list to see what mode the system is in? -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] arm: omap4: allow disabling MPU local timer if 32K timer is enabled
On Sat, Feb 11, 2012 at 6:26 PM, Russell King - ARM Linux li...@arm.linux.org.uk wrote: Have you actually checked the tick rate of your timer in /proc/interrupts? Have you checked /proc/timer_list to see what mode the system is in? After checking, the system works at periodic mode, but I still don't know why it can't be in one shot mode. Seems a single clock_event_device can't work well at system with more than one CPU, so the patch doesn't make sense, please ignore it. thanks, -- Ming Lei -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
