On 04/12/2016 05:42 AM, Grygorii Strashko wrote:
> The commit 55ee7017ee31 ("arm: omap2: board-generic: use
> omap4_local_timer_init for AM437x") unintentionally changes the
> clocksource devices for AM437x from OMAP GP Timer to SyncTimer32K.
>
> Unfortunately, the SyncTimer32K is starving from frequency deviation
> as mentioned in commit 5b5c01359152 ("ARM: OMAP2+: AM43x: Use gptimer
> as clocksource") and, as reported by Franklin [1], even its monotonic
> nature is under question (most probably there is a HW issue, but it's
> still under investigation).
>
> Taking into account above facts It's reasonable to rollback to the use
> of omap3_gptimer_timer_init().
I tested this patch and was not able to reproduce this issue after
rebooting the AM437 GP evm 30 times. I then tried without this patch and
the issue showed up after rebooting the board for the 5th time.
Tested-by: Franklin S Cooper Jr. <fcooper@xxxxxx>
>
> [1] http://www.spinics.net/lists/linux-omap/msg127425.html
> Cc: Felipe Balbi <balbi@xxxxxxxxxx>
> Cc: Lokesh Vutla <lokeshvutla@xxxxxx>
> Reported-by: Cooper Jr., Franklin <fcooper@xxxxxx>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
> ---
> arch/arm/mach-omap2/board-generic.c | 2 +-
> arch/arm/mach-omap2/timer.c | 7 +++++--
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
> index bab814d..60f5e83 100644
> --- a/arch/arm/mach-omap2/board-generic.c
> +++ b/arch/arm/mach-omap2/board-generic.c
> @@ -306,7 +306,7 @@ 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 = omap4_local_timer_init,
> + .init_time = omap3_gptimer_timer_init,
> .dt_compat = am43_boards_compat,
> .restart = omap44xx_restart,
> MACHINE_END
> diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
> index 6261e93..7cc055c 100644
> --- a/arch/arm/mach-omap2/timer.c
> +++ b/arch/arm/mach-omap2/timer.c
> @@ -500,16 +500,19 @@ void __init omap3_secure_sync32k_timer_init(void)
> }
> #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)
> void __init omap3_gptimer_timer_init(void)
> {
> __omap_sync32k_timer_init(2, "timer_sys_ck", NULL,
> 1, "timer_sys_ck", "ti,timer-alwon", true);
> + if (of_have_populated_dt())
> + clocksource_probe();
> }
> #endif
>
> #if defined(CONFIG_ARCH_OMAP4) || defined(CONFIG_SOC_OMAP5) || \
> - defined(CONFIG_SOC_DRA7XX) || defined(CONFIG_SOC_AM43XX)
> + defined(CONFIG_SOC_DRA7XX)
> static void __init omap4_sync32k_timer_init(void)
> {
> __omap_sync32k_timer_init(1, "timer_32k_ck", "ti,timer-alwon",
>
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