Re: [PATCH 03/10] ARM: smp_twd: Divorce smp_twd from local timer API

Tony Lindgren
2013-03-12T17:06:52Z

* Stephen Boyd <sboyd@codeaurora.org> [130311 18:25]:
> On 03/11/13 15:50, Tony Lindgren wrote:
> > * Stephen Boyd <sboyd@codeaurora.org> [130311 15:22]:
> >> Ok. qemu works for me before applying my patches. I've added this into
> >> the series before this patch to fix the boot issue.
> > OK thanks:
> >
> >
>
> Actually, it's worse. From reading the code it looks like quite a few
> other machines register a clockevent and get jiffies going so they can
> calibrate the twd. I also see that Rob Herring's pull request to move
> smp_twd to CLKSRC_OF_DECLARE is going to conflict with any changes I
> make in the board files. I think we need to make the twd use the
> late_time_init callback if there is no clock rate and ignore the other
> patch I sent out a few hours ago. Basically, squash this into this 3/10
> patch.

Looks reasonable to me to keep things working.

Regards,

Tony

> ----8<-----
>
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index a1185d3..c58918f 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -90,8 +90,10 @@ static int twd_timer_ack(void)
> return 0;
> }
>
> -static void twd_timer_stop(struct clock_event_device *clk)
> +static void twd_timer_stop(void)
> {
> + struct clock_event_device *clk = __this_cpu_ptr(twd_evt);
> +
> twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
> disable_percpu_irq(clk->irq);
> }
> @@ -265,8 +267,9 @@ static void twd_get_clock(struct device_node *np)
> /*
> * Setup the local clock events for a CPU.
> */
> -static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
> +static void __cpuinit twd_timer_setup(void)
> {
> + struct clock_event_device *clk = __this_cpu_ptr(twd_evt);
> int cpu = smp_processor_id();
>
> /*
> @@ -275,9 +278,9 @@ static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
> */
> if (per_cpu(percpu_setup_called, cpu)) {
> __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
> - clockevents_register_device(__this_cpu_ptr(twd_evt));
> + clockevents_register_device(clk);
> enable_percpu_irq(clk->irq, 0);
> - return 0;
> + return;
> }
> per_cpu(percpu_setup_called, cpu) = true;
>
> @@ -302,20 +305,18 @@ static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
> 0xf, 0xffffffff);
> enable_percpu_irq(clk->irq, 0);
>
> - return 0;
> + return;
> }
>
> static int __cpuinit twd_timer_cpu_notify(struct notifier_block *self,
> unsigned long action, void *hcpu)
> {
> - struct clock_event_device *evt = this_cpu_ptr(twd_evt);
> -
> switch (action & ~CPU_TASKS_FROZEN) {
> case CPU_STARTING:
> - twd_timer_setup(evt);
> + twd_timer_setup();
> break;
> case CPU_DYING:
> - twd_timer_stop(evt);
> + twd_timer_stop();
> break;
> }
>
> @@ -348,8 +349,15 @@ static int __init twd_local_timer_common_register(struct device_node *np)
>
> twd_get_clock(np);
>
> - /* Immediately configure the timer on the boot CPU */
> - twd_timer_setup(this_cpu_ptr(twd_evt));
> + /*
> + * Immediately configure the timer on the boot CPU, unless we need
> + * jiffies to be incrementing to calibrate the rate in which case
> + * setup the timer in late_time_init.
> + */
> + if (twd_timer_rate)
> + twd_timer_setup();
> + else
> + late_time_init = twd_timer_setup;
>
> return 0;
>
>
> --
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