ARM: OMAP2+: Get rid of custom OMAP_32K_TIMER_HZ (8f0de0d6) · Commits · 戴 / test

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 <arnd@arndb.de> Cc: Russell King <linux@arm.linux.org.uk> Cc: John Stultz <john.stultz@linaro.org> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by:

Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by:

Lokesh Vutla <lokeshvutla@ti.com> Signed-off-by:

Tony Lindgren <tony@atomide.com>

arch/arm/Kconfig

+0 −1

Original line number	Diff line number	Diff line
		@@ -1650,7 +1650,6 @@ 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

arch/arm/plat-omap/Kconfig

+0 −9

Original line number	Diff line number	Diff line
		@@ -177,15 +177,6 @@ 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

arch/arm/plat-omap/include/plat/timex.h

+0 −8

Original line number	Diff line number	Diff line
		@@ -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 * 100000UL)
		#endif

		#endif /* __ASM_ARCH_OMAP_TIMEX_H */

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