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 <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>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 67874b8..c407edb 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -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

diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig
index 665870d..1fbac36 100644 (file)
--- a/arch/arm/plat-omap/Kconfig
+++ b/arch/arm/plat-omap/Kconfig
@@ -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

diff --git a/arch/arm/plat-omap/include/plat/timex.h b/arch/arm/plat-omap/include/plat/timex.h
index 6d35767..e27d2da 100644 (file)
--- 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 * 100000UL)
-#endif
 
 #endif /* __ASM_ARCH_OMAP_TIMEX_H */