Subject: [PATCH V2 4/4] ARM: OMAP2+: AM43x: Use gptimer as clocksource

From: [email-masked] (Tony Lindgren)
Date: Thu, 13 Feb 2014 15:19:19 -0800

* Lokesh Vutla <[email-masked]> [140207 02:24]:
> From: Rajendra Nayak <[email-masked]>
> 
> The SyncTimer in AM43x is clocked using the following two sources:
> 1) An inaccuarte 32k clock (CLK_32KHZ) derived from PER DPLL, causing system
>    time to go slowly (~10% deviation).
> 2) external 32KHz RTC clock, which may not always be available on board like
>    in the case of ePOS EVM
> 
> Use gptimer as clocksource instead, as is done in the case of AM335x
> (which does not have a SyncTimer). With this, system time keeping works
> accurately.

Hmm doesn't this also mean that PM for any deeper idle states won't
work properly?

Regards,

Tony
 
> Signed-off-by: Rajendra Nayak <[email-masked]>
> Signed-off-by: Lokesh Vutla <[email-masked]>
> ---
>  arch/arm/mach-omap2/board-generic.c |    2 +-
>  arch/arm/mach-omap2/timer.c         |    3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
> index 8e3daa1..5679464a 100644
> --- a/arch/arm/mach-omap2/board-generic.c
> +++ b/arch/arm/mach-omap2/board-generic.c
> @@ -229,7 +229,7 @@ DT_MACHINE_START(AM43_DT, "Generic AM43 (Flattened Device Tree)")
>  	.init_late	= am43xx_init_late,
>  	.init_irq	= omap_gic_of_init,
>  	.init_machine	= omap_generic_init,
> -	.init_time	= omap3_sync32k_timer_init,
> +	.init_time	= omap3_gptimer_timer_init,
>  	.dt_compat	= am43_boards_compat,
>  MACHINE_END
>  #endif
> diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
> index 74044aa..b62de9f 100644
> --- a/arch/arm/mach-omap2/timer.c
> +++ b/arch/arm/mach-omap2/timer.c
> @@ -604,7 +604,8 @@ OMAP_SYS_32K_TIMER_INIT(3_secure, 12, "secure_32k_fck", "ti,timer-secure",
>  			2, "timer_sys_ck", NULL);
>  #endif /* CONFIG_ARCH_OMAP3 */
>  
> -#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX)
> +#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX) || \
> +	defined(CONFIG_SOC_AM43XX)
>  OMAP_SYS_GP_TIMER_INIT(3, 2, "timer_sys_ck", NULL,
>  		       1, "timer_sys_ck", "ti,timer-alwon");
>  #endif
> -- 
> 1.7.9.5
>