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

Stephen Boyd
2013-03-12T01:20:49Z

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.

----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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