[PATCH] ARM: smp_twd: make sure timer is stopped before registering it

[Shilimkar, Santosh]

On Thu, Dec 22, 2011 at 8:01 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
> On secondary CPUs, the Timer Control Register is not reset
> to a sane value before the timer is registered, and the TRM
> doesn't seem to indicate any reset value either. In some cases,
> the kernel will take an interrupt too early, depending on what
> junk was present in the registers at reset time.
>
> The fix is to set the Timer Control Register to 0 before
> registering the clock_event_device and enabling the interrupt.
>
> Problem seen on VE (Cortex A5) and Tegra.
>
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
>  arch/arm/kernel/smp_twd.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index a8a6682..2442bbb 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -167,6 +167,8 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk)
>
>        twd_calibrate_rate();
>
> +       __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
> +
Is it because of junk value in register or something programmed as part of the
calibrate function. I suspect it might be because of what's getting programmed
as part of calibrate function.

Regards
Santosh