Re: [PATCH] ARM: OMAP2+: Get rid of custom OMAP_32K_TIMER_HZ
On 01/31/13 17:32, Santosh Shilimkar wrote: > The timekeeping doesn't depend on HZ value in presence of fine grained > clocksource and hence there should not be any time drift because of HZ > value which was chosen to be divisor of 32768. > > OMAP has been using HZ = 128 value to avoid any time drift issues > because of 32768 HZ clock. But with various measurements performed > with HZ = 100, no time drift is observed and it also proves the > point about HZ not having impact on time keeping on OMAP. Great! I had the same patch in my tree already for several months, but I was afraid to send it as I had no time to test it thoroughly. These kind of things are always scary to send without proper testing... Thank you very much for testing and sending this out! > > Very informative thread on this topic is here: > https://lkml.org/lkml/2013/1/29/435 > > Special thanks to John Stulz, Arnd Bergmann and Russell King for their > valuable suggestions. > > Cc: Arnd Bergmann > Cc: Russell King > Cc: John Stultz > Cc: Tony Lindgren If it still not too late: Acked-by: Igor Grinberg > > Signed-off-by: Santosh Shilimkar > Tested-by: Lokesh Vutla > --- > arch/arm/Kconfig|1 - > arch/arm/plat-omap/Kconfig |9 - > arch/arm/plat-omap/include/plat/timex.h |8 > 3 files changed, 18 deletions(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index b35b27f..5493164 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -1648,7 +1648,6 @@ config HZ > int > default 200 if ARCH_EBSA110 || ARCH_S3C24XX || ARCH_S5P64X0 || \ > ARCH_S5PV210 || ARCH_EXYNOS4 > - default OMAP_32K_TIMER_HZ if ARCH_OMAP && OMAP_32K_TIMER > default AT91_TIMER_HZ if ARCH_AT91 > default SHMOBILE_TIMER_HZ if ARCH_SHMOBILE > default 100 > diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig > index 67c859c..ce66eb9 100644 > --- a/arch/arm/plat-omap/Kconfig > +++ b/arch/arm/plat-omap/Kconfig > @@ -147,15 +147,6 @@ config OMAP3_L2_AUX_SECURE_SERVICE_SET_ID > help > PPA routine service ID for setting L2 auxiliary control register. > > -config OMAP_32K_TIMER_HZ > - int "Kernel internal timer frequency for 32KHz timer" > - range 32 1024 > - depends on OMAP_32K_TIMER > - default "128" > - help > - Kernel internal timer frequency should be a divisor of 32768, > - such as 64 or 128. > - > config OMAP_DM_TIMER > bool "Use dual-mode timer" > depends on ARCH_OMAP16XX || ARCH_OMAP2PLUS > diff --git a/arch/arm/plat-omap/include/plat/timex.h > b/arch/arm/plat-omap/include/plat/timex.h > index 6d35767..e27d2da 100644 > --- a/arch/arm/plat-omap/include/plat/timex.h > +++ b/arch/arm/plat-omap/include/plat/timex.h > @@ -28,14 +28,6 @@ > #if !defined(__ASM_ARCH_OMAP_TIMEX_H) > #define __ASM_ARCH_OMAP_TIMEX_H > > -/* > - * OMAP 32KHz timer updates time one jiffie at a time from a secondary timer, > - * and that's why the CLOCK_TICK_RATE is not 32768. > - */ > -#ifdef CONFIG_OMAP_32K_TIMER > -#define CLOCK_TICK_RATE (CONFIG_OMAP_32K_TIMER_HZ) > -#else > #define CLOCK_TICK_RATE (HZ * 10UL) > -#endif > > #endif /* __ASM_ARCH_OMAP_TIMEX_H */ > -- Regards, Igor. -- 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: OMAP2+: Get rid of custom OMAP_32K_TIMER_HZ
* Arnd Bergmann [130131 07:41]: > On Thursday 31 January 2013 21:02:00 Santosh Shilimkar wrote: > > The timekeeping doesn't depend on HZ value in presence of fine grained > > clocksource and hence there should not be any time drift because of HZ > > value which was chosen to be divisor of 32768. > > > > OMAP has been using HZ = 128 value to avoid any time drift issues > > because of 32768 HZ clock. But with various measurements performed > > with HZ = 100, no time drift is observed and it also proves the > > point about HZ not having impact on time keeping on OMAP. > > > > Very informative thread on this topic is here: > > https://lkml.org/lkml/2013/1/29/435 > > > > Special thanks to John Stulz, Arnd Bergmann and Russell King for their > > valuable suggestions. > > > > Cc: Arnd Bergmann > > Cc: Russell King > > Cc: John Stultz > > Cc: Tony Lindgren > > Acked-by: Arnd Bergmann > > Thanks so much for looking into this! Great thanks for checking it Santosh! Applying into omap-for-v3.9/soc. Tony -- 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: OMAP2+: Get rid of custom OMAP_32K_TIMER_HZ
On Thursday 31 January 2013 21:02:00 Santosh Shilimkar wrote: > The timekeeping doesn't depend on HZ value in presence of fine grained > clocksource and hence there should not be any time drift because of HZ > value which was chosen to be divisor of 32768. > > OMAP has been using HZ = 128 value to avoid any time drift issues > because of 32768 HZ clock. But with various measurements performed > with HZ = 100, no time drift is observed and it also proves the > point about HZ not having impact on time keeping on OMAP. > > Very informative thread on this topic is here: > https://lkml.org/lkml/2013/1/29/435 > > Special thanks to John Stulz, Arnd Bergmann and Russell King for their > valuable suggestions. > > Cc: Arnd Bergmann > Cc: Russell King > Cc: John Stultz > Cc: Tony Lindgren Acked-by: Arnd Bergmann Thanks so much for looking into this! -- 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
[PATCH] ARM: OMAP2+: Get rid of custom OMAP_32K_TIMER_HZ
The timekeeping doesn't depend on HZ value in presence of fine grained clocksource and hence there should not be any time drift because of HZ value which was chosen to be divisor of 32768. OMAP has been using HZ = 128 value to avoid any time drift issues because of 32768 HZ clock. But with various measurements performed with HZ = 100, no time drift is observed and it also proves the point about HZ not having impact on time keeping on OMAP. Very informative thread on this topic is here: https://lkml.org/lkml/2013/1/29/435 Special thanks to John Stulz, Arnd Bergmann and Russell King for their valuable suggestions. Cc: Arnd Bergmann Cc: Russell King Cc: John Stultz Cc: Tony Lindgren Signed-off-by: Santosh Shilimkar Tested-by: Lokesh Vutla --- arch/arm/Kconfig|1 - arch/arm/plat-omap/Kconfig |9 - arch/arm/plat-omap/include/plat/timex.h |8 3 files changed, 18 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index b35b27f..5493164 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1648,7 +1648,6 @@ config HZ int default 200 if ARCH_EBSA110 || ARCH_S3C24XX || ARCH_S5P64X0 || \ ARCH_S5PV210 || ARCH_EXYNOS4 - default OMAP_32K_TIMER_HZ if ARCH_OMAP && OMAP_32K_TIMER default AT91_TIMER_HZ if ARCH_AT91 default SHMOBILE_TIMER_HZ if ARCH_SHMOBILE default 100 diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig index 67c859c..ce66eb9 100644 --- a/arch/arm/plat-omap/Kconfig +++ b/arch/arm/plat-omap/Kconfig @@ -147,15 +147,6 @@ config OMAP3_L2_AUX_SECURE_SERVICE_SET_ID help PPA routine service ID for setting L2 auxiliary control register. -config OMAP_32K_TIMER_HZ - int "Kernel internal timer frequency for 32KHz timer" - range 32 1024 - depends on OMAP_32K_TIMER - default "128" - help - Kernel internal timer frequency should be a divisor of 32768, - such as 64 or 128. - config OMAP_DM_TIMER bool "Use dual-mode timer" depends on ARCH_OMAP16XX || ARCH_OMAP2PLUS diff --git a/arch/arm/plat-omap/include/plat/timex.h b/arch/arm/plat-omap/include/plat/timex.h index 6d35767..e27d2da 100644 --- a/arch/arm/plat-omap/include/plat/timex.h +++ b/arch/arm/plat-omap/include/plat/timex.h @@ -28,14 +28,6 @@ #if !defined(__ASM_ARCH_OMAP_TIMEX_H) #define __ASM_ARCH_OMAP_TIMEX_H -/* - * OMAP 32KHz timer updates time one jiffie at a time from a secondary timer, - * and that's why the CLOCK_TICK_RATE is not 32768. - */ -#ifdef CONFIG_OMAP_32K_TIMER -#define CLOCK_TICK_RATE(CONFIG_OMAP_32K_TIMER_HZ) -#else #define CLOCK_TICK_RATE(HZ * 10UL) -#endif #endif /* __ASM_ARCH_OMAP_TIMEX_H */ -- 1.7.9.5 -- 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
